Okay, so Kriegsmarine was like a really big group of people who worked together for the German Navy during World War II. They had special boats called ships and submarines that they used to fight against the enemy. They were led by a man named Admiral Karl Doenitz, who was like their captain. They had lots of different jobs like protecting their own ships and attacking the enemy's ships. They had different people doing different things like sailors who drove and controlled the boats, and people who fixed the boats when they were broken. The Kriegsmarine fought in lots of big battles during the war, but in the end, they lost and had to stop fighting.