After World War I, European and American military strategists debated what would happen if civilians became the main targets of air-bombing attacks. An influential Italian military writer, General Giulio Douhet, actually argued for the sustained bombing of civilians. He predicted that they would become quickly demoralized by such bombing and would force their leaders to surrender. Despite the theories of Douhet, most at this time felt that bombing civilians was uncivilized and should be prohibited. In 1923, Britain, France, Italy, Japan, and the United States agreed to a set of rules for air warfare. One article prohibited “bombing from the air for the purpose of terrorizing the civilian population . . . or of injuring noncombatants. . . ." The participating governments, however, never ratified these rules, so they were not legally binding. At the Geneva Disarmament Conference of 1932, most of the world's powers agreed that air attacks on civilians violated the laws of war. But the conference broke up before approving a final agreement.
Zeppelins were used to drop explosive ordinance on cities in Belgium and England during the First World War.
As airplanes in the interwar period became faster, larger, and more powerful, Douhet's vision of the aircraft as the decisive force in war became a possibility. In the years leading up to World War II, Japan became the first power to attack civilians from the air. In 1932, Japanese warplanes bombed a worker district in Shanghai, China, an incident that produced worldwide outrage. The outrage did not stop Japan from bombing civilian areas of other Chinese cities. In 1936, Italian dictator Mussolini ordered an attack on the largely defenseless east African country of Ethiopia. When Mussolini's warplanes struck the capital city, causing many civilian casualties, the world again condemned the slaughter of innocent people. The following year, the Germans bombed Guernica, an event made famous by Pablo Picasso's famed antiwar painting of the tragic attack on the town's populated marketplace during the Spanish Civil War (1936-1939).
Picasso's Guernica, 1937
Modern “blitzkrieg" meant lightning-fast assaults, not only by land troops and tank divisions, but also by warplanes bombing both military and civilian targets. The Germans hit the Polish capital of Warsaw especially hard, with indiscriminate bombing killing thousands of civilians. In May 1940, the Nazis invaded the Netherlands on their way to France. Easily overcoming Dutch defenders, the Germans still bombed the center of Rotterdam with explosive and fire bombs, killing tens of thousands. Failing to destroy Britain's Royal Air Force, and thus, indefinitely postponing an attempt at invading the British Isles, Hitler's air force struck London and other English cities with terrifying night bombing raids. The bombing of London, the main target of German planes, cost the lives of 30,000 people.
The "Blitz" in London, 1941.
Driven from the continent, the British could only strike back by mounting their own bombing campaign against the Germans. At first, the Royal Air Force (RAF) attempted to bomb only specific German military and industrial targets in daytime raids. But the lack of fighter support made these raids risky, and bombs often missed their precise targets because of poor bombsights. For the rest of the war, the British concentrated on the systematic widespread destruction of German cities by RAF nighttime air raids, a strategy called "area bombing". One reason the British took this fateful step was to "delouse" the German people, which hopefully would shatter their morale and will to continue the war. The clearest demonstration of the destructiveness of British area bombing occurred in 1943 during three night raids on Hamburg, Germany. On the second night of bombing, something unexpected happened. The fire bombs dropped by 731 RAF bombers started thousands of fires. They merged to create a huge firestorm, sucking up oxygen and generating hurricane force winds. Many who did not burn to death were asphyxiated in underground bomb shelters. The firestorm killed more than 40,000 people in one night.
"The firestorm is incredible, there are calls for help and screams from somewhere but all around is one single inferno.
To my left I suddenly see a woman. I can see her to this day and shall never forget it. She carries a bundle in her arms. It is a baby. She runs, she falls, and the child flies in an arc into the fire.
Suddenly, I saw people again, right in front of me. They scream and gesticulate with their hands, and then - to my utter horror and amazement - I see how one after the other they simply seem to let themselves drop to the ground. (Today I know that these unfortunate people were the victims of lack of oxygen). They fainted and then burnt to cinders.
Insane fear grips me and from then on I repeat one simple sentence to myself continuously: 'I don't want to burn to death'. I do not know how many people I fell over. I know only one thing: that I must not burn."
(Margaret Freyer, resident of Dresden, recalling the February 1945 raid)
While the U.S. Army Air Force attempted to maintain a longstanding policy of daytime precision bombing using accurate bombsights and escorts from fighter planes. The Americans believed that the most effective way to destroy the enemy's ability to continue the war was to strike specific targets like aircraft factories and oil refineries. Despite high American bomber losses, American attempts at “precision” bombing were able to heavily damage key sectors of the German industry. The lack of aviation fuel and gasoline dramatically reduced the ability of German planes and tanks to operate in the field by 1945. However, Germany's overall industrial capacity did not dramatically decline until many of the factories were captured by Allied ground forces (see data below.)
An American B-24 Liberator bomber conducting the dangerous low-level raid on the oil refinery at Ploesti, Romania, 1943.
The air campaign on Japan, however, proved to be different. Initial strikes on Japanese cities failed due to strong air defenses, mechanical failures, and a strong jet stream which blew the bombs off-course. Led by General Curtis LeMay, a new strategy was implement to fly the huge B-29 bombers during the night and at low altitudes to drop massive amounts of explosive and flammable incendiary bombs on the predominantly-wooden cities.
On the night of March 9-10, 1945, LeMay's B-29 bombers attacked Tokyo, a city of 6 million people. Nearly 600 bombers dropped 1,665 tons of fire bombs on the Japanese capital. An hour after the first fires started, the conflagration spread beyond the target area, and LeMay’s desired firestorm was achieved with devastating results. The citizenry in the target area ran through the streets in panic, desperate to find any form of safety from the searing heat. The heat, which is reported to have reached an unimaginable temperature of 1,800 degrees in some locations, sucked the oxygen out of the air, asphyxiating those it did not simply roast to death. The clothes on people’s backs, those that weren’t on fire from the actual bombs, literally burst into flames from the heat. The glass in windows began to liquify. The superheated air and cyclonic winds from the firestorm blew the liquified glass into the air, where it fell on people like some terrible rain, embedding itself into their scalps where it continued to melt into the hair and skin. The resulting firestorm destroyed 16 square miles of the city and killed 100,000 people, more than died at Hiroshima or Nagasaki from atomic bombs a few months later. Most of the victims were women, children, and old men. The B-29 crew members put on oxygen masks to keep from vomiting at the smell of burning human flesh.
Source(s): Encyclopedia Britannica