The events of World War 2 proved beyond any doubt that the strategic
bombing campaign greatly contributed to the Allies' ultimate victory
over Nazi Germany. British night bombing raids and daylight carpet
bombing missions flown by the USAAF crews rained destruction on German
cities killing thousands of civilians in the process. Amidst this
massive loss of civilian life the destruction of German industrial
targets seemed almost like a side note. The arms race that kicked off
even before the war began produced military aircraft capable of reaching
ever higher operational ceilings. At first thin air at high altitudes
was the domain of reconnaissance machines, but before long fighter and
bomber aircraft began to venture there as well. In those early days
high-altitude flight was a challenging business: it required the use of
pressurized cockpits and boosted powerplants
capable of delivering adequate power at altitude.