[41]
Truman also ran the camp canteen with Edward Jacobson, a clothing store clerk he knew from Kansas City. Unlike most canteens funded by unit members, which usually lost money, the canteen operated by Truman and Jacobson turned a profit, returning each soldier's initial $2 investment and $10,000 in dividends in six months.[35] At Fort Sill, Truman met Lieutenant James M. Pendergast, nephew of Tom Pendergast, a Kansas City political boss, a connection that had a profound influence on Truman's later life.[42][43]

Truman in uniform, c. 1918
In mid-1918, about one million soldiers of the American Expeditionary Forces (AEF) were in France.[44] Truman was promoted to captain effective April 23,[45] and in July became commander of the newly arrived Battery D, 129th Field Artillery, 35th Division.[46][47] Battery D was known for its discipline problems, and Truman was initially unpopular because of his efforts to restore order.[35] Despite attempts by the men to intimidate him into quitting, Truman succeeded by making his corporals and sergeants accountable for discipline. He promised to back them up if they performed capably, and reduce them to private if they did not.