Joining the
Kriegsmarine in 1935, Grade served aboard the
cruiser Emden, a training ship, as an engineering cadet until 1936. During
World War II, he was chief engineer (LI) of the U-boats
U-96 and
U-183. Grade was the last surviving eyewitness to the submarine's patrols. In 2017, he published his hitherto unknown diaries, written during operations on
U-96. He achieved Germany-wide awareness in 2018, when his story was picked up by the media as part of the remake of
Das Boot. After the end of his assignments on U-96, Grade completed two more patrols on U-183 and then trained U-boat crews as a technical instructor for the submarine training flotilla until the end of the war. In 1958, he was accepted into the newly formed
German Navy to lead the development of new submarines there. In 1970, shortly before his retirement, he worked on the revision of
Lothar-Günther Buchheim's novel
Das Boot. When he retired in 1974, he held the rank of
Kapitän zur See. Grade was married in
Eckernförde and had two children who were born during World War II. In his last years, he lived in a retirement home in
Bornheim. Grade died on 13 October 2023, at the age of 107. ==References==