In Which We Serve (1944)

After the opening montage, the story begins with the HMS Torrin being severely damaged while engaging the German enemy in the battle for Crete. It then focuses on a group of survivors who cling exhausted to a life raft in the water, dodging the bullets from a Nazi plane. The recollections of three of the crew in particular (Captain Kinross, CPO Hardy, and Ordinary Seaman Shorty Blake) are detailed through a series of watery flashbacks.
Captain Kinross recalls his times at home with his wife and family, the time his ship helped to bring the army home from Dunkirk, Christmas services, and the night the crew fought an unseen enemy in the stormy North Atlantic, bringing home the Torrin badly damaged and with thirty dead.
The memories of CPO Walter Hardy and OIS Shorty Blake overlap: there are recollections of how Hardy's niece met and later married Shorty Blake, of their families in Plymouth, of Hardy's wife and her disagreeable mother, and of the night that bombs falling over Plymouth killed Hardy's wife and miraculously left Shorty a new father. Finally the ship sinks, and in time the crew is rescued, eventually to be dispersed to new assignments.