The Giant Step is the 30th in the Turn Of Fate television short movies and is from 1958 (bottom centre image).
Based in a submarine, Gunner Smith (Robert Ryan) initially refuses to go ashore with Karl Wallace (Michael Landon) in search of a poisonous snake so that the medics can develop a vaccine ahead of an invasion.
Smith blames Wallace for the death of his best friend.
In the end Smith saves his life twice, firstly from Japanese soldiers and then from a snake bite.
Movie pages here.