"The 7th is made up of Phantoms" season 5, episode 130, The Twilight Zone
As a child I grew up on a diet of Warner Brother Westerns, shows like TZ scared me but this episode always fascinated me. I love the scene where the tank crew goes over the hill to join Custer's command carrying M1 carbines and 1911s.
Rod Serling's closing tag
“ Sergeant William Connors, Trooper Michael McCluskey, and Trooper Richard Langsford, who on a hot afternoon in June made a charge over a hill - and never returned. Look for this one under 'P' for phantom, in a historical ledger located in a reading room known as the Twilight Zone."