In 1940, with Britain standing alone against Germany, Winston Churchill stated correctly that "The fighters are our salvation but the bombers alone provide the means of victory". For years before the war, the Royal Air Force's Bomber Command spoke highly of precision bombing and strategic bombing, of destroying the enemy's war industry and morale, but when war came, it was rather small and equipped with old bombers. After suffering heavy losses in day bombardments early in the war, it retreated to night bombing which further reduced the possibility of precision bombing of specific strategic targets. Even worse than that, only after two years of war, and following many intelligence reports of the inefficiency of the British bombing campaign, Churchill's scientific advisor initiated a systematic study of bombing accuracy (the Butt Report), which included both systematic analysis of photos of bombed targets and measured bombing tests. The results were quite shocking.
Only a third of the bombers bombed within a radius of five miles from the target. Low clouds, fog, and industrial smoke even reduced this ratio to just one of ten bombers, and only about 1% of the bombs actually hit the large designated target. In other words, despite the allocation of great resources to build many heavy bombers and train their crews, and the efforts and heavy casualties of bomber crews, they simply missed their targets and wasted their efforts.
In response, bomber command got a new commander, Arthur "Bomber" Harris, and a new tactic of area bombing was adopted. Instead of targeting specific large strategic targets such as aircraft factories, bomber command since then targeted entire large cities, from a list of Germany's industrial cities, because the study proved that only a large city was big enough to hit by night bombing. In addition to the indiscriminate destruction of industrial targets in the bombed cities, Harris and others firmly believed that the horror and heavy civilian casualties of the bombardment will also break German morale, although the bombardment of British cities in 1940 did not erode British morale, and he persisted with this misbelief despite evidence that it didn't break German morale either.
In addition to area bombing of cities, Harris also pushed for further improvement and deployment of electronic navigation systems based on radio beams and radars, and also developed operating tactics designed to reduce bomber losses. Most of those new methods and tactics relied on using the Mosquito and its advantages over the heavy bombers:
One of the methods to increase the accuracy of the heavy bombers was the Pathfinder Force, an idea copied from a German tactic used in the bombardment of British cities earlier in World War 2. The Pathfinder Mosquitoes flew ahead of the main bomber formations and marked the targets by bombing them with incendiary bombs. The greater accuracy of the Pathfinders was achieved either by flying at very high altitude or at low altitude.
If navigation relied on navigation beams transmitted from Britain, their range was limited by the horizon, and since the higher the bomber flew the further was its horizon, and since the Mosquito could reach much higher altitude than a heavy bomber, the use of Mosquito Pathfinders significantly extended the limited operational radius of this navigation method.
For further targets, Mosquito crews, mostly with experienced navigators, flew to the targets at low altitudes and visually identified them and marked them with incendiary bombs. This was much safer to do with a fast Mosquito than with a heavy bomber.
Another method involved placing a senior navigator, nicknamed the master bomber, in a Mosquito which loitered at high speed over the target area to visually observe the bombardment and guide the following waves of bombers with aiming corrections. Doing this with an aircraft other than Mosquito would have been suicidal.
Also, in order to divert German night fighters from the heavy bomber formations, Mosquito bombers were used for diversion bombing attacks of other cities. And finally, as mentioned earlier, Mosquito night fighters were used for hunting the German night fighters sent to intercept the heavy bombers.
Bomber command used the De Havilland Mosquito to improve the very poor accuracy of the heavy bombers and to reduce their losses, but it refused to consider the alternative, which was finally adopted only after World War 2 and dominates modern air power since. The alternative was to replace the big and slow and expensive heavy bombers with the Mosquito as Bomber command's main bomber. The points in favor of this alternative were also clearly presented by group commander Bennett, as a comparison between the Mosquito and the Lancaster, which was the best British heavy bomber:
Bennett added that any way you do the math with those data, "It's quite clear that the value of the Mosquito to the war effort is significantly greater than that of any other aircraft in the history of aviation". In the German side, Erhard Milch, the deputy head of the Luftwaffe, said about the Mosquito "I fear that one day the British will start attacking with masses of this aircraft". But in one of the greatest allied mistakes in World War 2, bomber command persisted with its heavy bombers, and less than 1/4 of the Mosquitoes produced were of bomber types.
Bomber command dropped a total of 1.2 million tons of bombs in World War 2. Given the above 1% hit precision statistic, it actually means dropping just 12,000 tons of bombs on real strategic targets. Since accuracy was later improved thanks to Mosquito Pathfinders, let's assume for a moment that the amount of bombs which hit strategic targets was 50% higher. A quick calculation shows that a force of only 1000 Mosquito bombers of the 7781 Mosquitoes produced, could drop this amount on the same targets with high precision in just ten bombing missions each, at a fraction of the cost in blood, material resources, and time. This demonstrates the tremendous potential lost by using most of the Mosquitoes for every possible mission other than as a main strategic day and night precision bomber. The entire course of World War 2 could be drastically different. The Mosquito bomber enabled the British bomber command to do exactly what it wanted to do, and destroy the entire German military industry in a precision bombing campaign even before American B-17s and B-24s began their costly day bombing campaign over Germany.
After World War 2, area bombing was transformed to nuclear bombing, which does not require precision, and was never used since the nuclear destruction of Hiroshima and Nagasaki. But conventional air bombardment, both tactical and strategic, is entirely dominated since the end of World War 2 by precision bombing, which is so much more efficient, both in military terms, and by not killing countless enemy civilians as was done in World War 2.
Modern bombers no longer rely on gun turrets to engage an enemy fighter which intercepted them. Instead, all modern bombers, like the De Havilland Mosquito, rely on their speed and agility, and also on electronic warfare and stealth, to avoid being intercepted in the first place.
Modern bombers, just like the Mosquito, bomb their targets either at high speed and very low altitude, in order to achieve great precision while minimizing their exposure to detection and anti-aircraft fire, or by launching cruise missiles which do so, or at high altitude, like Mosquito Pathfinders did, relying on electronic navigation and targeting systems which evolved from the radio beams of World War 2 to today's satellite-based systems, which work by exactly the same principles, but with unlimited range and much greater precision.
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