Who is Germans from Islands in the Stream and what is their importance?

The Germans massacre a small island village, an act which Thomas writes off as coming from desperate men. He later thinks that fanaticism drives the Germans more than fear, yet they are only known by their trail and actions. The evidence indicates that the Germans are good sailors who take care of their own, which is to be expected from any nation. In their last act of firing on Thomas's boat, desperation plays an undeniable role. They need a boat.