F Troop was set at Fort Courage, Kansas, a fictional United States Army outpost in the West, in 1865, after the American Civil War ended. There was a town of the same name next door to the fort.
The commanding officer at Fort Courage is the gallant but chronically clumsy and accident-prone Captain Wilton Parmenter, the descendant of a long line of military leaders. He was awarded the Medal of Honor after accidentally instigating the final charge at the Battle of Appomattox. As a private, he was ordered to fetch his commanding officer's laundry. When he rode away on horseback to accomplish the errand, the pollen in the air caused him to sneeze repeatedly. He sneezed loudly just as he passed a group of soldiers, and they mistook this sneeze for the order "Charge!" His superiors, wishing to reward his action, promoted him to captain and gave him command of remote Fort Courage, a dumping ground for the least useful soldiers.