 He said that Captain Rathke was obsessed with receiving a Knight's Cross of the Iron Cross medal for sinking 100,000 tonnes-worth of enemy ships.Richter said that the captain's obsession eventually led to recklessness, ultimately resulting in the boat's sinking.Richter also said he was the last man out of the U-boat before it sank; those still on board were already dead, or perished in the boat as it sank.