John Thomas — General in the Continental Army

1724–1776

General John Thomas was an officer in the Massachusetts Militia and the Continental Army during the first year of the American Revolutionary War. Thomas is most well-known for securing Dorchester Heights in Boston, forcing the British to evacuate the city in 1776.

John Thomas, General, USA, American Revolution

This illustration depicts General John Thomas. Image Source: New York Public Library Digital Collections.

Who was General John Thomas?

John Thomas (1724–1776) was a General in the Continental Army born in Marshfield, Massachusetts. Initially trained in medicine, he became a soldier during the French and Indian War and achieved the rank of Colonel in the colonial forces. Thomas was recognized for his leadership during the Siege of Boston and was appointed Brigadier General in the Continental Army by the Second Continental Congress. Thomas led American forces during the occupation of Dorchester Heights, which forced the British to leave Boston. Afterward, he briefly led the Northern Army during the Invasion of Canada. However, he died of smallpox at Sorel on June 2, 1776.

Facts About General John Thomas

These facts summarize the life and career of General John Thomas, a key leader of American forces in the early days of the American Revolutionary War.

Early Life and Medical Career

  • John Thomas was born in Marshfield, Massachusetts in 1724.
  • Thomas studied medicine under Dr. Simon Tufts in Medford, Massachusetts.
  • He started his military career as a surgeon’s mate in 1746, during King George’s War, and served the Annapolis Royal garrison.
  • He continued service under General Samuel Waldo in Nova Scotia.

Service During the French and Indian War

  • During the French and Indian War, Thomas returned to the military in 1755 as a Lieutenant.
  • He served as the Colonel of a provincial regiment in 1759–1760.
  • Thomas commanded a provincial regiment when General Jeffrey Amherst led his army down Lake Champlain in 1760.
  • He commanded troops during the Battle of Montreal on September 8, 1760.

Return to Massachusetts

  • Following the French and Indian War, John Thomas was primarily engaged in his medical practice in Kingston, Massachusetts for 15 years.

American Revolution

  • John Thomas joined the Sons of Liberty during the American Revolution.
  • On February 9, 1775, he was appointed as a General in the Massachusetts Militia by the Massachusetts Provincial Congress.

American Revolutionary War and the Siege of Boston

  • Following the Battles of Lexington and Concord, Massachusetts Militia forces laid siege to British forces in Boston.
  • John Thomas was appointed Colonel of a regiment raised in Plymouth County as part of the New England Army of Observation.
  • Thomas was named Lieutenant General and Second-in-Command of Massachusetts troops on May 25, 1775.
  • During the Siege of Boston, he commanded the right wing of the army located at Roxbury and blocked the British from moving out of the city over Boston Neck.

Congress Organizes the Continental Army

As the Siege of Boston dragged on, the Massachusetts Provincial Congress appealed to the Continental Congress and asked it to take over the Army of Occupation. The Continental Congress responded by establishing the Continental Army, of which the New England Army of Observation was a part. Thomas was named a Brigadier General in the Continental Army on June 22.

Important dates in the organization of the Continental Army are:

  • June 14 — The first troops for the new army were approved, consisting of six companies of riflemen from Pennsylvania, Maryland, and Virginia.
  • June 15 — George Washington was elected Commander-in-Chief. 
  • June 17Artemas Ward was appointed as a Major General and Second-in-Command to Washington. Horatio Gates was appointed Adjutant General with the rank of Brigadier General. Charles Lee was appointed as a Major General and Third-in-Command.
  • June 19Philip Schuyler was appointed as the 3rd Major General and Israel Putnam was appointed as the 4th Major General.
  • June 22 — Brigadier Generals were commissioned: Seth Pomeroy, Richard Montgomery, David Wooster, William Heath, Joseph Spencer, John Thomas, John Sullivan, and Nathanael Greene.

Pomeroy turned down the appointment to Brigadier General, and Congress later adjusted the rankings, moving Thomas ahead of William Heath. This would play a role in Thomas eventually being sent to Canada to take command of the Northern Army during the Invasion of Quebec.

Fortification of Dorchester Heights

  • After arriving at Cambridge on July 2, General George Washington took command of the American forces, which became part of the Continental Army.
  • On March 4, 1776, General Washington put John Thomas in command of the operation to mount cannons on Dorchester Heights in Boston.
  • That night, Thomas led 3,000 men across Dorchester Neck to occupy Dorchester Heights.
  • By placing cannons on the heights, the Americans could fire on British ships in Boston Harbor.
  • Soon after, British forces agreed to evacuate Boston.

Thomas and the Invasion of Canada

  • On March 6, 1776, John Thomas was promoted to Major General in the Continental Army.
  • Thomas was ordered to lead troops north and take command of the Northern Army, which was laying siege to Quebec.
  • He left Roxbury on March 22 and made his way to Albany, New York, arriving there on March 28. From there he went to Quebec.
  • Thomas arrived at Quebec City on May 1, replaced General David Wooster, and took command of 2,500 men.

Thomas and the Retreat from Quebec

  • On May 2, a fleet of British warships and troop transports entered the river and sailed toward Quebec City. Among the troops were General John Burgoyne, General Friedrich Riedesel, and the first Hessian mercenaries.
  • Thomas was notified and he started to pull his troops back from Quebec City, hoping to regroup, receive reinforcements, and launch another attack.
  • The first British troops landed on March 6.
  • American forces panicked and fled, starting the retreat south toward Montreal.
  • Thomas paused his march and tried to organize his army at Deschambault, 40 miles southwest of Quebec City, along the St. Lawrence River. From there, he marched along the river to Sorel, arriving there on May 17. 
  • During the entire march, his men were harassed by gunfire from British Marines and warships on the river. 
  • The Americans were also plagued by smallpox, which continued to spread throughout the camp.
  • Thomas contracted smallpox and was no longer able to lead the army.
  • General John Sullivan arrived at Fort St. John on June 1, with 3,000 reinforcements.
  • Command of the Northern Army was transferred from Thomas to Sullivan.

Death of John Thomas

  • John Thomas died from smallpox on June 2, 1776, at Sorel.

Citation Information

The following information is provided for citations, including APA Style, Chicago Style, and MLA Style.

  • Article Title John Thomas — General in the Continental Army
  • Date 1724–1776
  • Author
  • Keywords John Thomas, General, Continental Army, New England Army of Observation, Who was John Thomas, What did John Thomas do, When did John Thomas Die, Where did John Thomas join the Continental Army, Why is John Thomas important to the American Revolutionary War, How did John Thomas help end the Siege of Boston
  • Website Name American History Central
  • Access Date April 18, 2024
  • Publisher R.Squared Communications, LLC
  • Original Published Date
  • Date of Last Update March 26, 2024

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