Although the movie is set in World War Two, the basic situation on which the story is loosely based is that of the World War One naval battles of Coronel in the South Pacific and the Falkland Islands in the South Atlantic, both of which took place in 1914. As in the film, a British cruiser force was defeated in the first battle by a superior German force and then Royal Navy reinforcements sent from England allowed the British to triumph in the second encounter.
The trivia item below may give away important plot points.
The film has two endings, shown one after the other. In the first, Brown dies; in the other, he survives. In neither is the identity of his father explicitly stated, although many have assumed it's Saville.