Fortress returns from toughest day raid with one of its engines on fire Some of the fiercest air battles of the war were fought yesterday , January 11 , when Fortresses and Liberators attacked vital targets in North West Germany in great strength . Swarms of fighters came up to challenge the streams of bombers . Tactics of the Luftwaffe included planes trailing bombs on long cables , rocket planes and rockets . One of the Fortresses ' Rocky ' , reached home with its number 2 engine feathered and its number 4 on fire 12 January 1944