They Were Five by Jack Pinoteau

5.20

Now that the world conflict is over, five inseparable wartime buddies swear eternal friendship now to each other. But there's many a slip 'twixt the cup and the lip. Jean becomes a postman, Marcel a boxer, Roger an actor, André a student and Philippe remains what he has always been, a young man of good social standing. Roger, who can't find any role, is introduced through his singer sister Valérie, to Frédo, a shady nightclub owner.Roger soon becomes one of Frédo's henchmen. To make matters worse, he swipes Jean's fiancée, Simone. Marcel, who loses fight after fight, ends up joining Fredo's gang as well. André, who wanted to redeem the faults of his father during the Occupation, gets killed in the Indochina war. Marcel is shot down while taking part in a robbery. In her turn, Valérie is bumped off by an accomplice of Fredo and Roger is sent to jail.