The Pea Ridge Campaign was a six-month Union offensive in Missouri and Arkansas from December 28, 1861, to July 12, 1862. General Samuel R. Curtis drove Sterling Price’s Missouri State Guard out of Missouri, defeated Earl Van Dorn’s Army of the West at the Battle of Pea Ridge, and advanced across Arkansas. The campaign ended when Curtis occupied Helena, Arkansas, which became an important Union base for operations along the Mississippi River.