Hell in the Pacific (1968)

Plot:

Hell in the Pacific is set during World War II, a shot-down American pilot and a marooned Japanese navy captain find themselves stranded on the same small uninhabited island in the Pacific Ocean. Following war logic, each time the crafty Japanese devises something useful, he guards it to deny its use to the Yank, who then steals it, its proceeds or the idea and/or ruins it. Yet each gets his chance to kill and/or capture the other, but neither pushes this to the end.

Both Lee Marvin and Toshirô Mifune actually served in the Pacific during World War II, of course on opposing sides. Marvin's a US Marine. He was wounded during the war and received the Purple Heart during the Battle of Saipan in 1943. Mifune served in the Imperial Japanese Army Air Service.

Hell in the Pacific (1968) is Cast Away on Steroids

Isolation in extreme conditions allows for very telling studies of human beings, and potentially unpleasant philosophical conclusions. Marooning a character on an island will get you some dramatic results, and the only way to take it a step further is to maroon that character's worst possible enemy with him. That's what Hell in The Pacific proposes.

Directed by John Boorman
Starring: Lee Marvin, Toshirô Mifune