 The Kriegsmarine ( German navy ) had at least three surface ships in the Loire estuary : a destroyer , an armed trawler and a <unk> ( minesweeper ) , the latter being the guard ship for the port . On the night of the raid there were also four harbour defence boats and ten ships from the 16th and 42nd <unk> flotillas berthed in the basin , while two tankers were berthed inside the Normandie dock . The 6th and 7th U @-@ boat flotillas , commanded by <unk> Georg @-@ Wilhelm Schulz and Korvettenkapitän Herbert <unk> respectively , were permanently based in the port . It is not known how many submarines were present on the day of the raid . The submarine base had been inspected by the U @-@ boat Commander in Chief , <unk> Karl <unk> , the day before the raid . He asked what would they do if the base was subject to an attack by British Commandos . <unk> replied that " an attack on the base would be hazardous and highly <unk> " . 
