 Complete the following phrase:  The record of the Luftwaffe against naval combat vessels up to that point in the war was poor. In the Norwegian campaign, despite eight weeks of continuous air supremacy, the Luftwaffe sank only two British warships. The German aircrews were not trained or equipped to attack fast-moving naval targets, particularly agile naval destroyers or Motor Torpedo Boats MTB. The Luftwaffe also lacked armour-piercing bombs and their only aerial torpedo capability, essential for defeating larger warships, consisted of a small number of slow and vulnerable Heinkel He 115 floatplanes. The Luftwaffe made 21 deliberate attacks on small torpedo boats during the Battle of Britain, sinking none. The British had between 700 and 800 small coastal craft MTBs, Motor Gun Boats and smaller vessels, making them a critical threat if the Luftwaffe could not deal with the force. Only nine MTBs were lost to air attack out of 115 sunk by various means throughout the Second World War. Only nine destroyers were sunk by air attack in 1940, out of a force of over 100 operating in British waters at the time. Only five were sunk while 