The Dark Angel(1925)

Alan Trent (Ronald Colman), his cousin Gerald Shannon (Wyndham Standing) and neighbor Kitty Vane (Vilma Bánky) have grown up together, as close playmates When World War I starts, both Alan and Gerald enlist in the British Army as officiers, and Kitty sees them off to war. Many months later, Alan and Gerald come back to Kitty, on a short furlow. Alan and Kitty reveal their love for each other. Gerald (who's in love with Kitty, too) congratulates his friends. But before Kitty and Alan can arrange to be married the next day, the furlow is cut short and both men head back to the front lines. Weeks later, Gerald will not give Alan leave to marry Kitty. Still arguing, both men volunteer for a reconiscience raid into enemy lines, where a grenade goes off near Alan and appears to kill him. Gerald and Kitty mourn Alan's death. After the war ends, Gerald and Kitty become engaged to be married.