Severloh was safe in an almost impregnable concrete bunker overlooking the beach. He had an unimpeded view of the oncoming Allied forces. He was the last German soldier firing, and may have accounted for about 3,000 American casualties, almost three-quarters of all the US losses at Omaha. The Americans came to know him as the Beast of Omaha.
He fired for nine hours, using up all the 12,000 machine-gun rounds. The sea turned red with the blood from the bodies. When he had no more bullets for the machine-gun, he started firing on the US soldiers with his rifle, firing off another 400 rifle rounds at the terrified GIs.
As much as D-Day is mythologized in America, I have never heard a whisper of this story before. It's amazing to me that he wasn't killed upon capture.