 The Mediterranean U @-@ boat Campaign lasted approximately from 21 September 1941 to May 1944 . The Kriegsmarine tried to isolate Gibraltar , Malta , and Suez and disrupt Britain 's trade routes . More than sixty U @-@ boats were sent to interdict Allied shipping in the Mediterranean Sea . Many of these U @-@ boats were themselves attacked negotiating the Strait of Gibraltar controlled by Britain . Nine U @-@ boats were sunk while attempting passage and ten more were damaged . 
 The Mediterranean U @-@ boat Campaign lasted approximately from 21 September 1941 to May 1944 . The Kriegsmarine tried to isolate Gibraltar , Malta , and Suez and disrupt Britain <a href='null_genetive' title='1'><mark>'s</mark></a>trade routes . More than sixty U @-@ boats <a href='uninflect' title='2'><mark>were</mark></a> sent to interdict Allied shipping in the Mediterranean Sea . Many of these U @-@ boats <a href='uninflect' title='3'><mark>were</mark></a> themselves attacked negotiating the Strait of Gibraltar controlled by Britain . Nine U @-@ boats <a href='uninflect' title='4'><mark>were</mark></a> sunk while attempting passage and ten more <a href='uninflect' title='5'><mark>were</mark></a> damaged . 
The Mediterranean U @-@ boat Campaign lasted approximately from 21 September 1941 to May 1944 . The Kriegsmarine tried to isolate Gibraltar , Malta , and Suez and disrupt Britain  trade routes . More than sixty U @-@ boats was sent to interdict Allied shipping in da Mediterranean Sea . Many of these U @-@ boats was themselves attacked negotiating the Strait of Gibraltar controlled by Britain . Nine U @-@ boats was sunk while attempting passage and ten more was damaged .