Seeing as this has now become war film
related here's my choice:
Das Boot
A bridge too far
Ice cold in Alex
The longest day
Above us the waves
Reach for the sky
The cruel sea
The colditz story
633 Squadron
The Dambusters
The Cockleshell heroes
Angels One Five
Appointment in London
The wooden horse
Stalag 17
The Battle of Britain... My fave bit below... " thanks awfully old chap"