▁significantly ▁affected ▁tor ped o es , ▁by ▁throwing ▁them ▁off ▁course ▁or ▁making ▁them ▁run ▁too ▁deep ▁- ▁potentially ▁explaining ▁at ▁least ▁part ▁of ▁the ▁missed ▁sh ots ▁and ▁tor ped o ▁fail ures . ▁ ▁Four ▁sub mar ines ▁were ▁also ▁lost ▁- ▁three ▁ocean - going ▁sub mar ines ▁consisting ▁of ▁two ▁VII B s ▁and ▁one ▁IX B ▁along ▁with ▁one ▁older ▁II A . ▁ ▁Sub marine ▁order ▁of ▁battle ▁Operation ▁Hart mut ▁engaged ▁nearly ▁every ▁sub marine ▁in ▁Germany ' s ▁n avy ▁- ▁most ▁not ably , ▁both ▁older ▁Type ▁I A ▁sub mar ines ▁and ▁all ▁six ▁of ▁Germany ' s ▁II A ▁coast al ▁sub mar ines , ▁which ▁were ▁operating ▁as ▁training ▁boats ▁in ▁the ▁Balt ic . ▁Bo ats ▁which ▁were ▁initially ▁un available ▁for ▁action ▁at ▁the ▁beginning ▁of ▁the ▁operation ▁took ▁part ▁in ▁fer ry ing ▁supplies ▁or ▁pat rolling ▁later ▁on . ▁ ▁When ▁Hart mut ▁was ▁issued ▁on ▁ 6 ▁April ▁ 1 9 4 0 ▁the ▁German ▁plan ▁designated ▁the ▁U - boot wa ffe ▁into ▁eight ▁groups ▁( al ong ▁with ▁a ▁further ▁Group ▁Seven , ▁which ▁was ▁cancel led ). ▁ ▁U - Bo at ▁Group ▁One ▁Pat rol ▁Area : ▁Nar vik , ▁Har stad , ▁West f j ord , ▁V ags f j ord ▁ ▁U - 2 5 ▁- ▁one ▁of ▁only ▁two ▁Type ▁I A ▁sub mar ines ▁in ▁the ▁Kriegs marine . ▁Under ▁the ▁command ▁of ▁Vik tor ▁Sch