F Troop was set at Fort Courage, Kansas, a fictional United States Army outpost in the West, shortly after the American Civil War ended in 1865. There was a town of the same name next to the fort. The show is light on historical accuracy (e.g. the uniforms, weapons, and salute are incorrect for the period), but is heavy on humor.
The commanding officer is the gallant but clumsy and accident-prone Captain Wilton Parmenter (Ken Berry), descended from a long line of military officers. He was awarded the Medal of Honor after accidentally instigating the final charge at the Battle of Appomattox. Only a private, he was ordered to fetch his commanding officer's laundry. When he rode away, pollen in the air caused him to sneeze repeatedly. He sneezed loudly as he passed a group of soldiers, and they mistook his sneeze for an 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 Army's least useful soldiers.
Much of the humor derived from the schemes of Captain Parmenter's non-commissioned officers, Sergeant O'Rourke and Corporal Agarn, with the local Indian tribe, the Hekawis, alternately seeking to expand and conceal their illicit business, O'Rourke Enterprises. There are also struggles by Parmenter to exert his authority and escape the matrimonial plans of his girlfriend, shopkeeper–postmaster Jane Angelica Thrift, known as "Wrangler Jane".