Manifest Destiny and Its Legacy

Whigs, Democrats, and Westward Expansion

Manifest Destiny was the idea that America had a God-given right to establish itself across the entire continent, from sea to sea. The term was coined by newspaper editor John L. O’Sullivan in 1845 when he said: “Our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.”

By the mid-1830s, a new two-party system emerged with the Whig Party and the Democrat Party. While both parties grew out of the old Democratic-Republican Party, it was the Democrats who continued to favor limited government and the “common man.” Because of this, many small farmers and urban workers supported the Democrats. Meanwhile, the Whigs supported a market-driven economy and social order. The Democrats were the party of Andrew Jackson, while the Whigs were adamantly opposed to his policies.

Tensions with Great Britain resumed in the late 1830s over the involvement of Americans in the Canadian Insurrection (1837), the Caroline Affair (1837), the Aroostook War (1838–1839), and the Creole Mutiny (1841). The Webster-Ashburton Treaty (1842) resolved the border between Canada and the U.S., from the East Coast to the Rocky Mountains, and several other key issues.

In 1840, the Whigs nominated William Henry Harrison for President. He ran against Jackson’s successor, Martin Van Buren, and defeated him. Unfortunately, Harrison developed pneumonia and died 30 days into his term. 

At the time, there was no constitutional procedure for replacing a President who died in office. Vice President John Tyler assumed the office in a move known as the “Tyler Precedent.” The move led to criticism of Tyler from all sides. Members of the Whig Party referred to him as “His Accidency.” Tyler was constantly at odds with his party, which supported key elements of Henry Clay’s American System, including a National Bank and protective tariffs.

During Tyler’s Presidency, Americans started pushing westward, following the Oregon Trail and other Overland Trails to the Oregon Territory. This was followed by the Annexation of Texas, which expanded the nation’s borders further west.

In the Election of 1844, the Democrats nominated James K. Polk while the Whigs turned to Henry Clay. Polk ran on a platform that promised westward expansion and won the election. After Texas joined the Union, the Mexican-American War was fought over a disputed border. The war ended with the Treaty of Guadalupe Hidalgo and the Mexican Cession.

America now stretched across the continent, from the Original 13 Colonies to California. While this expanded the nation’s economic potential it also inflamed the growing division over slavery. The Wilmot Proviso attempted to ban slavery in the territory gained in the Mexican Cession, however, the act was defeated.

American Territorial Expansion and Conflict in the 1840s

• Territorial expansion was a major focus of American politics in the 1840s.
• Settlers moving into the disputed Oregon Territory worsened relations with Britain.
• Britain had claims in the Pacific Northwest.
• The push to annex Texas increased tension with Mexico.
• Mexico saw Texas as a province in revolt, not an independent republic.
• American interest in California contributed to open warfare with Mexico.
• The U.S. victory in the war added new territories to the nation.
• The acquisition of new lands raised questions about slavery in these areas.
• These tensions over slavery contributed to the Civil War in the 1860s.

The Accession of “Tyler Too’’

President Harrison’s Short Administration and Whig Party Struggles

• William Henry Harrison won the Presidential Election of 1840.
• His Vice President was John Tyler.
• After Harrison arrived in Washington, D.C., many of his supporters followed, demanding government jobs.
• Harrison was overwhelmed and struggled to handle the pressure.
• Whig Party leaders saw Harrison as a figurehead, with Daniel Webster as Secretary of State and Henry Clay leading in the Senate.
• Harrison had to remind Clay that he, not Clay, was President.
• Harrison fell ill with pneumonia shortly after taking office.
• Harrison’s presidency lasted only 4 weeks, the shortest in U.S. history.
• His death followed the longest inaugural address in American history.

AHC Note — William Henry Harrison’s “Log Cabin and Hard Cider” campaign featured mass rallies, complete with music, banners, lapel pins, souvenir dinnerware, and even log cabin-shaped whiskey bottles. His supporters coined the phrase “Tippecanoe and Tyler Too,” which helped him defeat Martin Van Buren.

AHC Note — Harrison’s political supporters sought jobs due to the Spoils System, which was still popular.

President John Tyler

• John Tyler became President after William Henry Harrison’s death.
• He was known as a Virginia gentleman, gracious but firm in his principles.
• Tyler once resigned from the Senate rather than follow orders he disagreed with from the Virginia legislature.
• He had switched from the Democratic Party to the Whig Party due to his dislike of Andrew Jackson.
• Critics claimed he was a Democrat pretending to be a Whig.
• This accusation was partly accurate, as both parties had members with varying views.
• Tyler belonged to the minority faction of the Whig Party, supporting States’ Rights.
• He was added to the Whig ticket to appeal to States’ Rights supporters.
• Many of Tyler’s supporters were influential Southern landowners.
• Tyler disagreed with the key positions of the Whig Party: he was against the national bank, protective tariffs, and internal improvements.

AHC Note — At the time, the Constitution did not specifically say the Vice President was to assume the Office of the President if the President died. This led to a debate as to whether or not Vice President John Tyler was the “Acting President” or if he was to take the Oath of Office and assume the Presidency. When Tyler arrived in Washington, D.C., he met with the members of President Harrison’s cabinet and took the Oath of Office, making him the 10th President of the United States. Tyler’s political enemies were outraged, and started calling him “His Accidency.” Former President John Quincy Adams wrote that Tyler was acting like he was “…President of the United States, and not Vice-President acting as President, which would be the correct style.” Eventually, both houses of Congress adopted resolutions affirming that Tyler was indeed the President. This created what is known as the “Tyler Precedent.”

John Tyler: A President Without a Party

The Whig Party’s Platform

• After winning the election, the Whigs revealed their platform, led by Henry Clay.
• The platform came from Clay’s leadership and was no surprise to observers.
• It emphasized a strong nationalistic agenda.

Tyler Battles Whigs Over the Bank

• Financial reform was the priority of the Whig Party.
• Congress quickly passed a law to end the independent treasury system.
• President Tyler agreed and signed the law.
• Henry Clay pushed a bill through Congress to establish a new Bank of the United States.
• Tyler opposed the centralized bank and vetoed the bill.
• A mob that supported the bill gathered near the White House, shouting in support of Clay and against Tyler’s veto.
• Whig leaders introduced a new bill for a “Fiscal Corporation” as a substitute for the “Fiscal Bank.”
• Tyler vetoed this new bill as well.

Tyler’s Increasing Isolation and Opposition

• Whigs criticized Tyler, calling him an “Executive Ass.”
• He was burned in effigy and received death threats.
• A widespread influenza outbreak was mockingly called the “Tyler grippe.”
• Democrats were pleased when a group of Whig politicians expelled Tyler was expelled from the Whig Party.
• An attempt to impeach Tyler was discussed in the House of Representatives.
• Tyler’s entire cabinet resigned, except for Secretary of State Daniel Webster, who was engaged in negotiations with England.

Tyler’s Veto of Black Tariff

• Tyler opposed the proposed Tariff of 1842 despite the need for additional revenue.
• The bill included a provision to distribute revenue from public land sales to the states.
• Tyler disagreed with using federal money in this manner and vetoed the bill.

AHC Note — Opponents of the Tariff of 1842 called it the “Black Tariff.” It replaced the rates established by the Compromise Tariff of 1833 with new rates intended to raise taxes on imports over 10 years.

Clay’s Revised Tariff Bill and Its Aftermath

• Clay and the Whigs redrafted the bill to address Tyler’s objections.
• The revised bill removed the distribution of money from land sales and redacted tariff rates.
• Tyler signed the revised bill due to the government’s need for revenue.
• As the economy improved, the demand for higher customs duties decreased.
• The Whig campaign slogan, “Harrison, Two Dollars a Day and Roast Beef,” was mocked by Democrats as “Ten Cents a Day and Bean Soup.”

A War of Words with Britain

Anti-British Sentiment in the 19th Century

• Hostility towards Britain frequently erupted in the 19th century and intensified by 1842.
• Anti-British feelings were fueled by memories of past wars.
• The decline of pro-British Federalists and the rise of Jacksonian Democrats contributed to the hostility.
• British travelers criticized American customs, such as tobacco spitting and slave auctions.
• Their critical travel books, widely read in both Britain and America, intensified American anger.

AHC Note — Charles Dickens toured the United States and Canada from January to June 1842. Dickens was critical of slavery and noted both North and South were complicit in the system. Dickens published his notes from the trip as American Notes for General Circulation. Dickens wrote Martin Chuzzlewit based on his experience in America.

The Third War with England

• British magazines exacerbated tensions by criticizing American flaws.
• American journals responded with their criticisms, leading to a “Third War with England,” fought through newspapers and publications.
• British authors, including Dickens, participated, driven partly by frustration over the lack of an American copyright law.

Economic Tensions

• In the 19th Century, America was a borrowing nation, while Britain was a lending nation.
• The Panic of 1837 led to several American states defaulting or repudiating their bonds.
• British critics, angered by American financial practices, created satirical verses about American borrowing and spending habits.

AHC Note — The Panic of 1837 was an economic depression caused by various factors, including a drop in the price of cotton, a rise in the cost of slaves, and British lenders restricting loans. Many Americans blamed the policies of Andrew Jackson for the depression.

The Canadian Insurrection of 1837

• In 1837, a brief insurrection occurred in Canada.
• Many Americans, eager to oppose Britain, provided military supplies or volunteered to fight.
• The U.S. government declared neutrality but popular support for the insurrection made it difficult for the government to uphold neutrality.

The Caroline Incident of 1837

• In 1837, a British force attacked the American steamer, the Caroline, which was supplying Canadian insurgents.
• The British set the Caroline on fire on the New York side of the Niagara River.
• The Caroline sank and one American was killed.
• The attack on the Caroline was seen as a breach of neutrality.
• Washington officials protested, but their efforts were largely ineffective.
• In 1840, Alexander McLeod, a Candian, was arrested in New York for his alleged role in the Caroline raid, and charged with murder.
• The London Foreign Office warned that executing McLeod would lead to war, as they considered the raiders to be a legitimate force.
• McLeod was eventually tried by New York and acquitted.
• Tensions flared again in 1841 when British officials in the Bahamas granted asylum to 130 slaves who had rebelled and captured the American ship Creole.

AHC Note — In 1841, the Creole, an American slave ship, was carrying 135 captive Africans to New Orleans. The Africans revolted and took control of the ship — the Creole Mutiny — which sailed to the Bahamas, where slavery was illegal. Upon arrival, the Africans were freed. However, this violated international law.

Manipulating the Maine Maps

The Webster-Ashburton Treaty was an 1842 agreement between the United States and Great Britain. It formally identified the border between Canada and the U.S., from the East Coast to the Rocky Mountains, and resolved several other key issues.

The Maine Boundary Dispute and the Aroostook War

• The Maine boundary dispute became a significant issue in the early 1840s.
• The British planned to build a road from Halifax to Quebec.
• The route ran through the Aroostook River Valley, which was claimed by both Maine and Canada.
• Lumberjacks clashed in the region, and local militias were called in to restore order.
• This small-scale conflict, known as the “Aroostook War,” nearly escalated into a full-scale war.

Lord Ashburton Sent to America

• In 1842, the London Foreign Office took a unique approach to address the crisis.
• They sent Alexander Baring, Lord Ashburton, a financier and diplomat, to Washington.
• Ashburton had personal connections to America through his marriage to a wealthy American woman.
• He quickly developed friendly relations with Secretary Daniel Webster, who had been well-received during a recent visit to Britain.

The Webster-Ashburton Treaty

• In 1842, Ashburton and Webster reached a compromise on the Maine boundary.
• The agreement allowed the U.S. to keep about 7,000 of the 12,000 square miles involved in the dispute.
• The British received less land but secured the route from Halifax to Quebec.
• The Caroline Affair, unresolved since 1837, was settled, and Britain agreed to compensate the United States with $110,330 for freeing the slaves from the Creole.
• An additional benefit of the treaty was the British ceding 6,500 square miles further west, which later proved to contain valuable Mesabi iron ore in Minnesota.

The Lone Star of Texas Shines Alone

Texas’s Fragile Status and Mexican Opposition

• Despite the Texas Revolution (1835–1836), Mexico refused to acknowledge the independent Republic of Texas.
• Mexico viewed it as a rebellious province and planned to reconquer it.
• Mexican officials threatened war if the United States tried to annex Texas.

Texas’s Diplomatic Efforts for Protection

• Texas maintained a costly military due to constant threats from Mexico.
• Outnumbered, Texans faced uncertainty about potential Mexican attacks.
• Mexico conducted two ineffective raids, indicating possible future threats.
• To secure protection, Texas sought diplomatic agreements with Britain and France.
• In 1839 and 1840, Texas signed treaties with France, Holland, and Belgium.

Britain, France, and Texas

• Both Britain and France sought to leverage Texas against the United States.
• The British wanted to use a relationship with Texas to counter the growing power of the United States, which threatened British territories in the Western Hemisphere.
• France was also interested in using Texas to divide and weaken America, aiming to fragment and militarize the continent.

British Interests in Texas

Although the Monroe Doctrine warned against European influence in the Western Hemisphere:

• British abolitionists sought to establish a presence in Texas, hoping to influence and free enslaved individuals, which could affect Southern slaves.
• British merchants viewed Texas as a potential free-trade area, which would allow them to avoid U.S. tariffs.
• British manufacturers saw Texas as a potential cotton-producing region, which would reduce their reliance on American cotton.

The Belated Texas Nuptials

The Texas Annexation was a series of events that led to Texas joining the United States as the 28th state in the Union on December 29, 1845. The annexation of Texas was a direct cause of the Mexican-American War and contributed to the growing section divide over slavery that led to the Civil War in 1861. However, annexation expanded the economy and increased safety for Americans living on the western frontier.

Texas as a Key Issue in the 1844 Presidential Campaign

• The threat of British influence made Texas a key issue in the 1844 Presidential Election.
• Opponents of westward expansion criticized the idea of annexing Texas, while some Southern supporters demanded it, using the slogan “Texas or Disunion.”
• The pro-expansion Democrat James K. Polk defeated Whig candidate Henry Clay.

Texas Annexation

• Outgoing President John Tyler, interpreting the narrow Democratic victory as a mandate for Texas acquisition, pursued annexation.
• Many “Conscience Whigs” were concerned that Texas would bolster the “slave power” in the Union, while “Cotton Whigs” sought to maintain economic ties with Southern Whigs who owned plantations.
• Unable to secure the two-thirds Senate vote for a treaty, Tyler opted for annexation via a joint resolution.
• This method required only a simple majority in both houses of Congress.
• After lively debate, the resolution passed in early 1845, and Texas was invited to join the Union as the 28th state.
• Mexican officials were furious.
• Many Americans had supported the move since 1838 but were wary of the threat of war with Mexico.

Oregon Fever Populates Oregon

The Oregon Country: A Contest of Claims

• The Oregon Country was a vast wilderness extending from the Rockies to the Pacific Ocean and from California north to the line of 54° 40′ (the current southern tip of Alaska’s panhandle).
• At various times, this expansive region was claimed by four nations: Spain, Russia, Britain, and the United States.

Decline of Claims in the Oregon Country

• Spain, the first to claim Oregon, ceded its claims to the United States in the Adams-Onis Treaty (1819).
• Russia withdrew to the line of 54° 40′ through treaties with the U.S. (1824) and Britain (1825).
• After these withdrawals, Britain and the United States remained the principal claimants to the Oregon Country.

British Claims to the Oregon Country

British claims to Oregon, particularly north of the Columbia River, were based on:

• Prior discovery and exploration
• Treaty rights
• Actual occupation
• The Hudson’s Bay Company dominated the Fur Trade in the region and traded with the Pacific Northwest’s Native American Indian tribes.

American Claims to the Oregon Country

Americans could assert their claims based on:

• Captain Robert Gray’s discovery of the Columbia River in 1792, named after his ship
• The Lewis and Clark Expedition (1804–1806), which traversed the Oregon Territory to the Pacific
• American presence in Oregon was bolstered by missionaries (Whitman Party) and settlers who reached the Willamette River valley in the 1830s.
• These missionaries intended to convert Indians to Christianity but also helped solidify American claims to Oregon with their presence.

AHC Note — In 1836, American missionaries, led by Marcus Whitman and his wife, Narcissa, took the Oregon Trail to the Willamette Valley. The Whitman Party was led by Benjamin Bonneville. During the journey, the Whitmans became the first people to use wagons to make the journey on the trail. Narcissa Whitman also became one of the first Anglo-American women to travel the entirety of the Oregon Trail. Once they arrived in the Willamette Valley, the Whitmans established a mission that was visited frequently by emigrants on their way west.

American and British Presence in Oregon

• American and British pioneers peacefully coexisted in Oregon
• During the Treaty of 1818 negotiations, the United States proposed dividing the territory at the 49th parallel.
• The British, who valued the Columbia River, rejected the proposal.
• As a result, a scheme for “joint occupation” was implemented, allowing both nations to share the territory while awaiting a future resolution.

Oregon Fever and the British Response

• In the early 1840s, “Oregon Fever” led to a surge of American settlers.
• Hundreds of pioneers traveled the 2,000-mile Oregon Trail in covered wagons.
• By 1846, about 5,000 Americans had settled south of the Columbia River.
• By the mid-1840s, the British had only about 700 subjects north of the Columbia River.
• Facing a significant disparity in population compared to American settlers, the British recognized the need for a peaceful settlement to avoid being overwhelmed.

AHC Note — The Oregon Trail is the most famous of the Overland Trails used by thousands of American pioneers who emigrated to Oregon and other western territories during the age of Manifest Destiny and Westward Expansion. Frontiersman Robert Stuart blazed it from 1812 to 1813 and was most popular from 1841 to 1869.

Contested Area of Oregon Country

• By 1845, only a small portion of the Oregon Country was still in dispute.
• It was a rough quadrangle bordered by the Columbia River, the 49th parallel, and the Pacific Ocean.
• Britain had proposed using the Columbia River as the boundary, while the U.S. had proposed the 49th parallel.
• The dispute over the Oregon Country was overshadowed in the 1844 Presidential Election by the debate over Texas Annexation.
• The slogan “Fifty-four Forty or Fight” was coined in 1846, two years after the 1844 election.

A Mandate (?) for Manifest Destiny

1844 Presidential Nominations

• In May 1844, the Whigs nominated Henry Clay as their candidate for President.
• The Democrats faced a deadlock at their convention in Baltimore.
• Eventually, the Democrats, led by pro-Texas southerners, nominated James K. Polk of Tennessee as their candidate.
• Polk was America’s first “dark horse” or “surprise” candidate.

James K. Polk’s Background and Campaign

• James K. Polk was not a complete unknown.
• He served as Speaker of the House of Representatives for four years and as Governor of Tennessee for two terms.
• He was known for his determination, industriousness, ruthlessness, and intelligence.
• He was supported by Andrew Jackson, his friend and neighbor, and was promoted by Democrats as another “Young Hickory.”
• The Whigs mocked him with the question, “Who is James K. Polk?” but soon learned his significance as the campaign progressed.

AHC Note — Many historians consider 11th U.S. President James K. Polk to be one of the more effective chief executives because he delivered on nearly all of his campaign promises.

Manifest Destiny and the 1844 Campaign

• Manifest Destiny became a key issue during the 1844 Presidential Campaign.
• Many Americans felt it was their mission to spread democratic institutions throughout North America and potentially to South America.
• This belief combined land acquisition desires with ideals of spreading “empire” and “liberty.”

AHC Note — “Manifest Destiny” is the idea that Americans had a “God-given right” — a divine right — to expand across the continent, from the East Coast to the West Coast, from “sea to shining sea,” planting democracy, capitalism, and Christianity along the way.

Expansionist Sentiments in the 1844 Campaign

• Expansionist Democrats, influenced by the idea of Manifest Destiny, advocated for the “Reannexation of Texas” and the “Reoccupation of Oregon” up to the line of 54° 40′.
• They used aggressive slogans like “All of Oregon or None.”
• The Democrats criticized Whig candidate Henry Clay as a “corrupt bargainer” and a slaveowner, despite their candidate, James K. Polk, also being a slave owner.

Whig Campaign Responses and Slogans

• The Whigs responded to the expansionist rhetoric with slogans such as “Hooray for Clay” and “Polk, Slavery, and Texas,” or “Clay, Union, and Liberty.”
• They propagated a false claim that a group of Tennessee slaves had been branded with the initials J.K.P. (James K. Polk) on their way to a southern market.

AHC Note — The story of slaves being branded with Polk’s initials is called the “Roorback Hoax.” It appeared in an article in the Ithaca Chronicle on August 21, 1844. The Chronicle published what it said was an excerpt from Roorback’s Tour Through the Western and Southern States in 1836, written by Baron Roorback. In the story, Roorback said he encountered a group of slaves that had been branded. Polk’s supporters investigated the story and found out it was a hoax. There was no Baroon Roorback, and there was no book.

The 1844 Election and the Annexation of Texas

• Henry Clay tried to navigate the issue of Texas by presenting conflicting positions:
  • He supported annexation to appeal to the South.
  • He advocated postponement to appease the North.
• This “straddling” approach was intended to balance competing interests but ultimately alienated both ardent expansionists and anti-slavery proponents.
• Polk narrowly defeated Clay in the 1844 Election, and Clay’s stance on Texas may have cost him.
• Clay lost New York State by just 5,000 votes, whereas the Liberty Party, which opposed the annexation of Texas, drew nearly 16,000 votes that might have otherwise supported Clay.
• Ironically, the anti-Texas stance of the Liberty Party contributed to Polk’s victory and, consequently, to the annexation of Texas.
• President John Tyler signed the joint resolution to annex Texas three days before he left office.

Polk the Purposeful

James K. Polk’s Characteristics and Achievements

• James K. Polk was serious and determined but was not considered brilliant. 
• His reluctance to delegate authority created problems for him.
• Polk campaigned for President on a four-point program and completed it in less than four years.

Walker Tariff Act of 1846

• One of Polk’s goals was to lower the tariff rates.
• His Secretary of the Treasury, Robert J. Walker, crafted a tariff-for-revenue bill.
• The bill reduced average rates of the Tariff of 1842 from roughly 32% to 25%.
• It was supported by low-tariff southerners and lobbied through Congress by Walker. 
• However, it faced strong opposition from the Whigs, especially in New England and the middle states, who feared it would ruin American manufacturing.
• The Walker Tariff of 1846 turned out to be an effective revenue generator, benefiting from economic boom times and increased imports.

Restoration of the Independent Treasury

• Polk aimed to restore the independent treasury, which had been discontinued by the Whigs in 1841.
• Pro-bank Whigs in Congress strongly opposed the restoration.
• Despite the opposition, Polk’s efforts were successful, and the independent treasury was reestablished in 1846 by the Independent Treasury Act.

Acquisition of California and Settlement of the Oregon Dispute

• Polk sought to acquire California, which was a key part of his expansionist agenda.
• He also aimed to resolve the Oregon boundary dispute with Britain.

Oregon Treaty

• Polk promised the “reoccupation” of Oregon, reaching up to 54° 40′.
• He proposed a compromise line of 49° but Britain rejected the offer.
• Eventually, the British reconsidered their position on Oregon.
• “Little Englanders” argued that the Columbia River was not as crucial as previously thought and that American expansion into Oregon seemed inevitable.
• Britain questioned the wisdom of fighting a war for the Oregon Territory, especially with the diminishing influence of the Hudson’s Bay Company.
• Early in 1846, Britain proposed the 49° line for the Oregon Territory.
• This annoyed Polk since he had suggested it earlier, so he left the decision to the Senate.
• The Senate accepted the offer and ratified the treaty, despite some opposition from those advocating for the “Fifty-four forty or fight!” slogan.

AHC Note — Polk’s Secretary of State James Buchanan successfully negotiated the Oregon Treaty, which ended the long-standing disputes between Great Britain and the United States regarding the U.S.-Canadian border in the Pacific Northwest.

Reactions to the Oregon Treaty

• Not all Americans were pleased with the Oregon Treaty. 
• Many in the Northwestern states, who strongly supported Manifest Destiny, viewed the compromise as a betrayal.
• Critics questioned why the United States pursued all of Texas but only part of Oregon, viewing the compromise as unequal.
• Senator Thomas Hart Benton of Missouri defended it, saying “Great Britain is powerful and Mexico is weak.”
• Although President Polk did not achieve the “fifty-four forty” boundary, he secured a peaceful and reasonable settlement, avoiding another war with Britain.

Misunderstandings with Mexico

Polk’s Interest in California

• Polk and other proponents of Manifest Destiny were interested in acquiring California from Mexico.
• California’s valleys and the San Francisco Bay were crucial for America’s expansion and future access to the Pacific Ocean.
• The San Francisco Bay was America’s gateway to Pacific trade and exploration.

California’s Population in 1845

• Approximately 13,000 Spanish-Mexicans lived in California.
• Around 75,000 Indians, who were in a state of decline, were also part of the population.
• Fewer than 1,000 foreigners, mostly Americans, resided in California.
• The presence of Americans suggested California could be brought into the Union. similar to Texas.

Polk’s Interest in California and Tensions with Mexico

• Polk wanted to buy California from Mexico.
• However, relations with Mexico were strained.
• The United States had claims amounting to approximately $3 million against Mexico for damages to American citizens and their property.
• Despite agreeing to assume most of this debt, the unstable Mexican government had defaulted on its payments.

AHC Note — When the United States annexed Texas, American officials hoped it would allow them to discuss the border with Mexico. However, annexation only heightened tension, especially over the “Nueces Strip” — the disputed territory between the Nueces River and the Rio Grande River. Mexico insisted the Nueces River was its northern border, while Texas believed it was roughly 100 miles further south, at the Rio Grande River. 

Tensions Over Texas

• A major point of contention between the United States and Mexico was the annexation of Texas.
• The Mexican government had warned of war if the U.S. acquired Texas and had expressed strong opposition to the annexation.
• Following the annexation of Texas, Mexico recalled its minister from Washington, severing diplomatic relations.

Boundary Dispute with Mexico

• The southwestern boundary of Texas during Spanish and Mexican rule had been the Nueces River.
• After annexation, Texans claimed the more southerly Rio Grande was the boundary.
• President Polk felt obligated to support the Texas claim.
• Mexicans considered all of Texas still under their control and regarded the dispute over the boundary rivers as trivial.
• To avoid escalating tensions, President Polk kept American troops out of the disputed area between the Nueces and the Rio Grande while there was hope for a peaceful resolution.

AHC Note — In the fall of 1845 (see Mexican-American War Timeline), John Black, the U.S. consul in Mexico, met with the Mexican Minister of Foreign Affairs, Manuel de la Peña y Pena. The meeting left Black with the impression that the Mexican Government was open to discussing several issues, including the border. Black notified the State Department that Mexico was ready to restore diplomatic relations

Polk’s Anxiety and Diplomatic Efforts

• Polk was troubled by rumors that Britain might seize California, which Americans would find unacceptable under the Monroe Doctrine.
• In late 1845, Polk sent John Slidell to Mexico City as a minister. Slidell’s instructions included offering up to $25 million for California and additional territory.
• The Mexican government refused to entertain Slidell’s offer, considering it an “insulting” proposition.

AHC Note — Slidell, who was fluent in Spanish, was instructed to offer $5 million for the New Mexico Territory, $20 million for California, and $5 million for the disputed territory in the Nueces Strip.

AHC Note — Any hope Slidell had of success was eliminated when General Mariano Paredes y Arrillaga led a successful coup. On December 30, President José Joaquin Herrera resigned and Paredes and his military forces marched into Mexico City on January 2. The next day, Paredes became the new President of Mexico, and he had no intention of negotiating with the United States.

American Blood on American (?) Soil

Polk’s Push for Conflict

• On January 13, 1846, Polk ordered General Zachary Taylor and 4,000 men to move from the Nueces River toward the Rio Grande, placing them near Mexican forces.
• Polk anticipated a clash, but none occurred.
• On May 9, 1846, Polk proposed asking Congress to declare war on the grounds of (1) unpaid claims by American citizens and (2) the rejection of Slidell’s offer by Mexico. These reasons were considered weak by critics.
• Two cabinet members expressed that they would prefer to declare war only if Mexican troops fired first.

The Spark of War

• On April 25, 1846, Mexican troops crossed the Rio Grande and attacked U.S. troops in what is known as the Thornton Affair.
• A small U.S. patrol of 63 soldiers was attacked by a larger Mexican force.
• 11 U.S. troops were killed.
• General Taylor sent a message to Polk, informing him of the hostilities.

AHC Note — The Thornton Affair — also known as the Carricitos Skirmish — was fought between the United States of America and Mexico from April 25 to April 26, 1846, during the Mexican-American War. It was the first engagement of the war and opened the Texas Campaign. Mexican forces won the battle, which led to the United States Declaration of War against Mexico on May 12, 1846.

Declaration of War and Public Response

• Polk asked Congress to declare war.
• Congress responded with overwhelming support for the war.
• Volunteers rallied with slogans such as “Ho for the Halls of the Montezumas!” and “Mexico or Death!”
• Even strong anti-slavery Whig areas were caught up in the war fever, although they later criticized what they termed “Jimmy Polk’s War.”
• Poet James Russell Lowell expressed his dismay at the shift in sentiment with the verse: “Massachusetts, God forgive her, She’s akneelin’ with the rest.”

Lincoln’s “Spot” Resolutions and Political Reactions

• Polk’s message to Congress focused on the attack on American soil, though it did not clarify the disputed nature of the territory.
• Abraham Lincoln, a Whig congressman from Illinois, introduced “spot” resolutions demanding information on the exact location where American blood was shed.
• Lincoln’s insistence on these resolutions earned him the nickname “spotty Lincoln,” and he was seen as a proponent of “spotted fever” due to his persistence.
• Many extreme anti-slavery Northerners, including some Whigs, accused Polk of dishonesty, referring to him as “Polk the Mendacious.”

Did Polk Provoke War?

• California was a key objective for Polk, who was determined to acquire it even though Mexico was unwilling to sell.
• Polk faced the option of using force or waiting for an American revolt in California.
• Delaying acquisition risked British intervention, which could have kept the U.S. from gaining California.
• While grievances with Mexico were significant, they were not insurmountable; however, Polk’s impatience led him to escalate the conflict.

Mutual Aspirations for War

• Mexico was also eager for conflict.
• Southwestern expansionists in the U.S. sought to “teach the Mexicans a lesson.”
• Mexicans wanted to humiliate the Americans, with hopes of defeating them and possibly freeing enslaved people.
• Mexico, with a sizable standing army and numerous generals, entertained ambitious plans, including invading the U.S. and complicating the conflict with Britain over Oregon.
• Despite bold rhetoric, the U.S. conquest of Mexico seemed unlikely, given the failed invasions of Canada during the War of 1812.
• Both the United States and Mexico were motivated by strong feelings of moral righteousness.
• Mexicans saw themselves as defending their honor against American aggression, believing their territory had been violated.
• Many Americans, conversely, viewed Mexico as the aggressor in the conflict, believing the U.S. was acting in defense.

The Mastering of Mexico

Polk’s Strategy and Santa Anna’s Double-Cross

• Polk hoped to avoid a prolonged war.
• He intended to fight a limited conflict and withdraw once California was secured.
• The exiled Mexican dictator, Antonio López de Santa Anna, offered to sell out his country if allowed to return to Mexico.
• Polk agreed to this scheme, hoping to capitalize on Santa Anna’s betrayal.
• However, upon returning to Mexico, Santa Anna betrayed the agreement and rallied the Mexican people for a strong defense.

Capture of Santa Fe

• In 1846, General Stephen W. Kearny led 1,700 troops along the Santa Fe Trail from Fort Leavenworth to Santa Fe.
• Kearny easily captured Santa Fe.
• Before Kearny could reach California, the region was already largely secured.

The Bear Flag Revolt

• Captain John C. Frémont, an explorer, was in California with a few dozen armed men at the outbreak of war.
• Frémont aided in the overthrow of Mexican rule in California, which is known as the “Bear Flag Revolt.”
• He worked with American naval officers and local Americans who had established the California Bear Flag Republic.

AHC Note — The Bear Flag Revolt was an armed uprising by American settlers, known as the “Osos,” in California against the Mexican government in 1846. It is called the “Bear Flag Revolt” because the Osos adopted a flag that had a black bear on it.

General Zachary Taylor’s Campaign

• General Zachary Taylor, known as “Old Rough and Ready” led the main American thrust in the war.
• After the Thornton Affair, Taylor advanced across the Rio Grande into Mexico.
• He achieved several victories before reaching Buena Vista.
• On February 22–23, 1847, Taylor’s weakened force of 5,000 men was attacked by approximately 20,000 Mexican troops led by Santa Anna.
• Despite severe difficulty, Taylor’s forces repulsed the Mexican attack.
• Taylor’s success at Buena Vista earned him the title “Hero of Buena Vista.”
• Afterward, rumors started that Taylor would be elected President in 1848 due to his exploits.

ACH Note — Taylor defeated Mexican forces at the Battle of Palo Alto (May 8, 1846), and the Battle of Battle of Resaca de la Palma (May 9, 1846). Taylor occupied Matamoros on May 18 and remained there until the summer. He went on to win the Battle of Monterrey (September 21–25, 1846) and the Battle of Buena Vista (February 22–23, 1847).

General Winfield Scott’s Campaign

• The American strategy aimed to deliver a decisive blow to Mexico by targeting its capital, Mexico City.
• General Taylor, skilled in leading smaller forces, was not suited for large-scale operations in northern Mexico’s semi-desert terrain.
• The command of the main expedition, which advanced from the coastal city of Vera Cruz, was given to General Winfield Scott.
• General Scott was a distinguished military leader, who had gained fame during the War of 1812.
• Scott’s campaign was successful despite challenges, including inadequate troop numbers, expiring enlistments, a larger enemy force, difficult mountainous terrain, disease, and political opposition.
• By September 1847, Scott led American forces to Mexico City.
• Scott is considered one of the most distinguished American military officers to serve between 1783 and 1861.

AHC Note — One reason President Polk replaced Taylor with Scott was Taylor was a Whig. Polk did not want him to earn credit for winning the war.

Fighting Mexico for Peace

Efforts to End the War

• Polk was eager to conclude the conflict as soon as his territorial objectives were met.
• He dispatched Nicholas P. Trist, the Spanish-speaking chief clerk of the State Department, to accompany General Scott’s army.
• Scott and Santa Anna negotiated an armistice after the Battle of Contreras (August 19, 1847) and the Battle of Churubusco (August 20, 1847).
• Santa Anna used the delay to strengthen his defenses around Mexico City.

AHC Note — U.S. forces won the Battle for Mexico City (September 14–15, 1847). On November 11, 1847, A new Mexican Congress was formed and an interim President, Manuel de la Pena y Pena, was elected. However, the movement toward peace negotiations was slow. Trist received a message from Polk, ordering him to return to the United States. However, Trist was convinced that the opportunity for peace would be lost, and he decided to defy the order and enter into peace talks. 

Treaty of Guadalupe Hidalgo

• Trist wrote a lengthy 65-page letter to Polk, justifying his actions and explaining why he was not returning immediately.
• Despite Polk’s anger, Trist took advantage of the opportunity and signed the Treaty of Guadalupe Hidalgo on February 2, 1848.
• Trist then sent the treaty back to Washington for approval.
• The treaty confirmed American control over Texas.
• It ceded a vast area stretching westward to Oregon and the Pacific Ocean, including California.
• This ceded territory represented about half of Mexico’s total land.
• The United States agreed to pay Mexico $15 million for this land.
• Additionally, the U.S. assumed $3,250,000 in claims by American citizens against Mexico.

AHC Note — The land transfer from Mexico to the United States is known as the “Mexican Cession.”

Senate Submission and Political Opposition

• Polk submitted the Treaty of Guadalupe Hidalgo to the Senate for approval.
• Anti-slavery Whigs, known as “Mexican Whigs” or “Conscience Whigs,” were vocally condemning the war.
• These Whigs had taken control of the House in 1847 and threatened to block military supplies.
• Such a move could have forced General Winfield Scott to retreat, potentially undermining American victories and the treaty’s benefits.

Approval of the Treaty and Political Divisions

• A growing faction of expansionists sought the acquisition of all of Mexico.
• Such a move would have imposed a costly and challenging policing burden on the United States.
• Southerners like John C. Calhoun recognized the potential backlash from anti-slavery activists and advocated for moderation.
• The Treaty of Guadalupe Hidalgo was approved by the Senate with a vote of 38 to 14.
• The treaty faced condemnation from two opposing groups: those desiring all of Mexico and those opposed to any expansion.

Payment for Victory and Its Implications

• Victors typically do not pay indemnities, especially after a conflict they believe was imposed upon them.
• Despite initially planning to offer $25 million before the war, Polk arranged to pay $18,250,000 after winning it.
• A key reason for the payment was the urgency to finalize the treaty with a functioning Mexican government before domestic opposition, especially from anti-slavery advocates, could undermine Polk’s expansionist goals.

Profit and Loss in Mexico

Impact and Legacy

• The Mexican-American War cost around 13,000 American lives, predominantly due to disease.
• It resulted in a substantial territorial gain for the United States, expanding its land area by about one-third, including Texas. This expansion was even greater than that achieved through the Louisiana Purchase (1803).

Legacy of the War

• The war served as a training ground for many officers who played key roles in the Civil War, including Captain Robert E. Lee and Lieutenant Ulysses S. Grant.
• The conflict validated the importance of the U.S. Military Academy at West Point, which produced well-trained officers.
• The U.S. Navy contributed by establishing a blockade that crippled Mexican ports.
• The Marine Corps, established in 1798, gained new recognition and is commemorated in its hymn with references to the Halls of Montezuma.

Military Conduct and Respect Earned

• The U.S. Army conducted the war effectively, avoiding major defeats and blunders despite significant challenges and long marches.
• British and other foreign critics updated their views on American military capabilities following the war.
• Respect between opposing armies grew, with Mexicans, despite poor leadership, showing valor.
• At Chapultepec near Mexico City, the young cadets (Los Niños) of the military academy demonstrated remarkable bravery, with all of them perishing in battle.

AHC Note — The Battle of Chapultepec (September 13, 1847), was fought at the site of Mexico’s National Military Academy and the last obstacle before Mexico City. Nearly all 800 Mexican defenders are killed, including 50 cadets from the Academy who are remembered as Los Ninos Heroes — The Boy Heroes.

Aftermath and Latin American Relations

• Many Mexicans harbor lasting resentment over the loss of roughly half their country, despite the payment received and the avoidance of losing even more land.
• The war significantly altered U.S.-Latin American relations, shifting from calm and even friendliness to growing suspicion.
• The United States began to be viewed as a threatening “Colossus of the North,” with Latin American countries increasingly seeing it as a greedy and unreliable power that might encroach on their territories.

Impact on the Slavery Issue

• The war intensified the debate over slavery, contributing to the sectional tensions that eventually led to the Civil War.
• Abolitionists criticized the conflict as a scheme by the Southern “slavocracy” to expand slavery into new territories.
• Although many American volunteers came from the South and Southwest, their presence was more a result of regional proximity than a deliberate conspiracy.

The Wilmot Proviso and Congressional Debates

• In 1846, as the Mexican War started, President Polk sought $2 million to negotiate a peace settlement.
• Representative David Wilmot of Pennsylvania introduced an amendment to this appropriation bill, known as the Wilmot Proviso.
• The Wilmot Proviso proposed that slavery should be prohibited in any territory acquired from Mexico.
• The amendment sparked intense debate and highlighted the growing conflict over the expansion of slavery into new territories.

The Impact of the Wilmot Proviso

• The Wilmot Proviso passed the House of Representatives twice but was blocked in the Senate.
• Southern members of Congress opposed the Proviso, fearing the loss of potential slave states.
• Anti-slavery advocates, both in Congress and the public, supported the Proviso, arguing against the extension of slavery.
• The Proviso gained widespread support in the Free States, becoming a symbol of the contentious debate over slavery in newly acquired territories.

AHC Note — Introduced by Democratic Congressman David Wilmot of Pennsylvania, the Wilmot Proviso would have banned the extension of slavery into any territories Mexico ceded to the U.S. after the Mexican-American War. Although never enacted by Congress, the Wilmot Proviso increased the division of the American political landscape along sectional lines, ultimately contributing to the onset of the Civil War.

The Road to the Civil War

• The war foreshadowed the Civil War, marking the beginning of deep divisions within the nation.
• President Polk’s achievements included acquiring California and the Southwest but heightened tensions over slavery.
• Ralph Waldo Emerson noted that “Mexico will poison us.”
• John C. Calhoun warned that Mexico’s acquisition could lead to “political death.”.
• The territory gained from Mexico became a source of tension, seen by some as a form of retribution, or “Santa Anna’s Revenge.”

Additional Resources for Manifest Destiny and Its Legacy

The notes on this page are based on the 16th edition of The American Pageant. We have expanded on the source material with additional details, corrections, and links to Encyclopedia Entries that explain topics in more detail. For more information, including terms and definitions, see the following:

• Advanced Placement United States History (APUSH) Units
• The South and the Slavery Controversy (1793–1860)
• Manifest Destiny and Its Legacy (1841—1848)
• Renewing the Sectional Struggle (1848–1854)
• Drifting Toward Disunion (1854–1861)
• Girding for War: The North and the South (1861–1865)
• The Furnace of Civil War (1861–1865)
• The Ordeal of Reconstruction (1865–1877)