Meanwhile, the maritime air battle against U-boats was being waged in cooperation with the Admiralty and RAF's Coastal Command. The Navy requested air raids against U-boat operating bases and construction yards, and the transferral of aircraft from Bomber Command to Coastal Command. Bomber Command and the Air Ministry were unwilling to give resources. A Cabinet-level compromise was eventually worked out and the Navy and Coastal Command were given enough resources to defeat the U-boats in May 1943.
In 1943 the strategic attack on Germany reached its peak, with attacks from America by day and Britain by night. During this period Bomber Command launched three major battles - the Battle of the Ruhr from March to June, the Battle of Hamburg from late July to early August, and the Battle of Berlin from November 1943 to March 1944.
In this period new navigational tools became available to enhance the accuracy of the British night attacks. A number of low-level precision raids took place, such as the attacks on the Ruhr Dams. At the same time the daylight attacks by the US 8th Air Force destroyed the fighter force of the German Luftwaffe in air-to-air combat.
Operation Overlord was the codename for the Allied invasion of northwest Europe which began (operationally) on June 6 1944 with the invasion of Normandy. The liberation of France in the same year seriously weakened German integrated night defences and navigation aids were sited in liberated France, allowing for deeper and more accurate bombing. Because the massive US strategic bombing, 'attack by day', had effectively destroyed the German day fighter force in 1943, Bomber Command was now able to operate by day as well as by night.
By July 1944 Bomber Command was launching large-scale attacks on German cities and had become a huge force made up of Halifax and Lancaster heavy bombers, with a 'light strike force' made up of the very fast, high-flying Mosquito medium bomber aircraft. There were now electronic aids for navigation and bomb aiming - the 'Path Finder Force' marked targets with a high degree of accuracy for heavy bombers to attack. Bomber Command was also used for special operations, and in November 1944 Lancaster bombers armed with special bombs sank the battleship Tirpitz. In this final and victorious phase of Bomber Command's war, an event occurred that has always remained controversial - the Dresden bombing.
Bomber Command made an heroic effort during the war and was an enormous boost to British morale. Having suffered massive losses, it continued to take the war to the heart of Germany, night after night. Bomber Command transformed airpower into a political and military weapon, and with the addition of massive destruction from a single nuclear bomb, strategic bombing was transformed into the ultimate political weapon.