Firebombing Firebombing is a bomb ing technique designed to damage a target , generally an urban area , through the use of fire , caused by incendiary device s , rather than from the blast effect of large bombs . Although simple incendiary bombs have been used to destroy buildings since the start of gunpowder warfare , World War II saw the first use of strategic bombing from the air to destroy the ability of the enemy to wage war . The Chinese wartime capital of Chongqing was firebombed by the Japanese starting in early 1939 . London , Coventry , and many other British cities were firebombed during the Blitz . Most large German cities were extensively firebombed starting in 1942 and almost all large Japanese cities were firebombed during the last six months of World War II . This technique makes use of small incendiary bomb s ( possibly delivered by a cluster bomb such as the Molotov bread basket ) . If a fire catches , it could spread , taking in adjacent buildings that would have been largely unaffected by a high explosive bomb . This is a more effective use of the payload that a bomber could carry . The use of incendiaries alone does not generally start uncontrollable fires where the targets are roofed with nonflammable materials such as tiles or slates . The use of a mixture of bombers carrying high explosive bombs , such as the British blockbuster bomb s , which blew out windows and roofs and exposed the interior of buildings to the incendiary bombs , are much more effective . Alternatively , a preliminary bombing with conventional bombs can be followed by subsequent attacks by incendiary carrying bombers . Tactics . Early in World War II many British cities were firebombed . Two particularly notable raids were the Coventry Blitz on 14 November 1940 , and the blitz on London on the night of 29 December / 30 December 1940 , which was the most destructive raid on London during the war with much of the destruction caused by fires started by incendiary bombs . During the Coventry Blitz the Germans pioneered several innovations which were to influence all future strategic bomber raids during the war . These were : The use of pathfinder aircraft with electronic aids to navigate , to mark the targets before the main bomber raid ; The use of high explosive bombs and air - mine s coupled with thousands of incendiary bombs intended to set the city ablaze . The first wave of follow - up bombers dropped high explosive bombs , the intent of which was knock out the utilities ( the water supply , electricity network and gas mains ) , and to crater the road - making it difficult for the fire engines to reach fires started by the follow - up waves of bombers . The follow - up waves dropped a combination of high explosive and incendiary bombs . There were two types of incendiary bombs : those made of magnesium and iron powders , and those made of petroleum . The high - explosive bombs and the larger air - mine s were not only designed to hamper the Coventry fire brigade , they were also intended to damage roofs , making it easier for the incendiary bombs to fall into buildings and ignite them . As Sir Arthur Harris , commander of RAF Bomber Command , wrote after the war : The development of the tactical innovation of the bomber stream by the RAF to overwhelm the German aerial defenses of the Kammhuber Line during World War II would have increased the RAF ' s concentration in time over the target , but after the lessons learned during the Blitz , the tactic of dropping a high concentration of bombs over the target in the shortest time possible became standard in the RAF because it was known to be more effective than spreading the raid over a longer time period . For example , during the Coventry Blitz on the night of 14 / 15 November 1940 , 515 Luftwaffe bombers , many flying more than one sortie against Coventry , delivered their bombs over a period of time lasting more than 10 hours . In contrast , the much more devastating raid on Dresden on the night of 13 / 14 of February 1945 by two waves of the RAF Bomber Command ' s main force , involved the bomb released at 22 : 14 , with all but one of the 254 Lancaster bombers releasing their bombs within two minutes , and the last one released at 22 : 22 . The second wave of 529 Lancasters dropped all of their bombs between 01 : 21 and 01 : 45 . This means that in the first raid , on average , one Lancaster dropped a full load of bombs every half a second and in the second larger raid that involved more than one RAF bomber Group , one every three seconds . The United States Army Air Forces ( USAAF ) officially only bombed precision targets over Europe , but for example , when 316 B - 17 Flying Fortress es bombed Dresden in a follow - up raid at around noon on the 14th of February , 1945 , because of clouds the later waves bombed using H2X radar for targeting . The mix of bombs to be used on the Dresden raid was about 40 % incendiaries , much closer to the RAF city - busting mix than the bomb - load usually used by the Americans in precision bombardments . This was quite a common mix when the USAAF anticipated cloudy conditions over the target . In its attacks on Japan , the USAAF abandoned its precision bombing method that was used in Europe before and adopted a policy of saturation bombing , using a mix of incendiaries and high explosives to burn Japanese cities to the ground . These tactics were used to devastating effect with many urban areas burned out . The first raid using low - flying B - 29 Superfortress bombers carrying incendiary bombs to drop on Tokyo was on the night of 24 / 25 February 1945 when 174 B - 29s destroyed around fifty square miles ( 150 km² ) of the city . Changing their tactics to expand the coverage and increase the damage , 279 B - 29s raided on the night of 9 / 10 March , dropping around 1 , 700 tons of bombs . Approximately 16 square miles ( 42 km² ) of the city were destroyed and 100 , 000 people are estimated to have died in the resulting firestorm , more than the immediate deaths of either the atomic bombings of Hiroshima and Nagasaki .