Four-engined heavy bombers became central to the ‘Total War’ experienced in 1939-45, allowing for the implementation of increasingly destructive strategic bombing. First employed by the Luftwaffe during the invasion of Poland, strategic bombing was soon adopted by the Allies as it became integral to the long-range combat necessary in the years prior to D-Day.
1. Heinkel He 177
In its fast-paced conquests at the start of the war and during the ‘Blitz’, Germany relied upon medium bombers such as the Heinkel He 111, Dornier Do 17 and Junkers Ju 88. Thereafter, the Luftwaffe gained only one heavy bomber, the Heinkel He 177, which operated from April 1942 but with very limited effect.
2. Vickers Wellington
The twin-engined Vickers Wellington was important to RAF Bomber Command from the outset of war and accounted for over half of the aircraft used in the first 1000-bomber raid on Cologne, in May 1942. It was gradually replaced in the European theatre by the four-engined Stirlings, Halifaxes and Lancasters, however.
3. Short Stirling
The Short Stirling was the RAF’s first four-engined bomber, meeting pre-war specifications that required a 14,000 lb bomb load capacity and a challenging range of 3,000 miles. First deployed in February 1941, a lack of power quartered its bomb load during long range flights and performance issues meant that it sustained particularly heavy casualties. It was gradually withdrawn from bombing duties through 1943, dropping 27,000 tonnes in total.
4. Handley Page Halifax
The Handley Page Halifax was deputy to the feted Avro Lancaster. A Halifax was first flown operationally on the night of 10 March 1941 in an attack on Le Havre, but this proved an inauspicious start as the aircraft was mistakenly shot down by an RAF fighter.
Despite ongoing improvements, the Halifax lacked speed and power, which limited its load capacity and made it a second choice option for Air Chief Marshal ‘Bomber’ Harris as he pursued the destruction of urban Germany. Still, it was used to drop almost ten times the weight of bombs achieved by the Stirling and was used by the RAF until 1961.
5. Avro Lancaster
The Avro Lancaster entered the war as a replacement for the Manchester, although the inadequacy of its predecessor almost led to the Avro production facility at Newton Heath being shut down before development. The decision against this action proved crucial to the British war effort as the new aircraft was central to the success of Allied bombing strategy from March 1942 onwards.
Its commodious bomb bay allowed it to carry the full gamut of RAF explosives, meaning that it could be deployed in both precision and, more commonly, indiscriminate area bombing.
Lancasters were key to several high-profile missions, including the attack on the Ruhr valley that compromised German resources on the eve of their eastern offensive in 1943 and was immortalised in the 1955 film Dam Busters. Eventually, they dropped over 600,000 tonnes before the end of the war.
6. Boeing B-17 Flying Fortress
The Boeing B-17 Flying Fortress was used by the RAF from 1941 with little success, but became essential to Allied bombing with the arrival of the USAAF in 1942 and earned an iconic reputation. They were integral to the American strategy of daylight precision bombing, although this was suspended due to extreme losses in late 1943.
The arrival of the P-51 Mustang in allowed the comparatively safe resumption of these operations. In Europe, B-17s matched ultimately the British Lancasters in terms of total bombs dropped. The Boeing B-29 Superfortress superseded the B-17 and was extremely advanced in comparison to most of its contemporaries, but was only employed in the Pacific War.
7. Consolidated B-24 Liberator
The other notable US heavy bomber was the Consolidated B-24 Liberator, which was used to great effect by the RAF in the Battle of the Atlantic. The USAAF deployed the B-24 alongside the B-17 as part of the strategic bombing campaign of 1942-5 over mainland Europe, where it also performed admirably thanks to its greater speed, range and bomb capacity than its more popular companion. Although B-24s counted for only a third of the USAAF heavy bomber presence in Europe, they dropped over 400,000 tonnes.