A line of seven army posts were established in 1848–49 after the Mexican War to protect the settlers of West Texas and included Fort Worth, Fort Graham, Fort Gates, Fort Croghan, Fort Martin Scott, Fort Lincoln and Fort Duncan. Fort Duncan was established on March 27, 1849, when Captain Sidney Burbank occupied the site with companies A, B, and F of the First United States Infantry. On November 14, 1849, the post was named Fort Duncan, after Col. James Duncan, a hero of the Mexican–American War.