In 1941 Charles Portal of the British Air Staff advocated that entire cities and towns should be bombed. Portal claimed that this would quickly bring about the collapse of civilian morale in Germany. Air Marshall Arthur Harris agreed and when he became head of RAF Bomber Command in February 1942, he introduced a policy of area bombing (known in Germany as terror bombing) where entire cities and towns were targeted.
One tactic used by the Royal Air Force and the United States Army Air Force was the creation offirestorms. This was achieved by dropping incendiary bombs, filled with highly combustible chemicals such as magnesium, phosphorus or petroleum jelly (napalm), in clusters over a specific target. After the area caught fire, the air above the bombed area, become extremely hot and rose rapidly. Cold air then rushed in at ground level from the outside and people were sucked into the fire.
In 1945, Arthur Harris decided to create a firestorm in the medieval city of Dresden. He considered it a good target as it had not been attacked during the war and was virtually undefended by anti-aircraft guns. The population of the city was now far greater than the normal 650,000 due to the large numbers of refugees fleeing from the advancing Red Army.
On the 13th February 1945, 773 Avro Lancasters bombed Dresden. During the next two days the USAAF sent over 527 heavy bombers to follow up the RAF attack. Dresden was nearly totally destroyed. As a result of the firestorm it was afterwards impossible to count the number of victims. Recent research suggest that 35,000 were killed but some German sources have argued that it was over 100,000.