1945: In the single deadliest air raid of World War II, 330 American B-29s rain incendiary bombs on Tokyo, touching off a firestorm that kills upwards of 100,000 people, burns a quarter of the city to the ground, and leaves a million homeless.

The raid also represented a tactical shift, as the Americans switched from high-altitude precision bombing to low-altitude incendiary raids.

Tokyo was the first of five incendiary raids launched in quick succession against the largest Japanese cities. Nagoya, Osaka and Kobe were also targeted – with Nagoya getting hit twice within a week. By the end of the war, more than 60 Japanese cities had been laid waste by firebombing.

The Tokyo raid, codenamed Operation Meetinghouse, began an aerial onslaught so effective that the American air command concluded by July 1945 that no viable targets remained on the Japanese mainland. But if the American objective was to shorten the war by demoralizing the Japanese population and breaking its will to resist, it didn't work. What had proven true in Germany proved equally true here: Morale was shaken by bombing, but once the shock passed, the war work went on.

The Americans began looking to incendiaries as their stockpiles of those weapons increased, and because the typically cloudy weather conditions that prevailed over Japan made precision bombing difficult at best.

Maj. Gen. Curtis LeMay, commander of the 21st Bomber Command, also argued that incendiary bombing would be particularly effective, because Japanese cities contained a lot of tightly packed, wooden structures that would burn easily when set alight.

He was right.

The B-29 bombers for the Tokyo raid were stripped of their defensive weapons and packed with various incendiary explosives, including white phosphorus and napalm, a new gasoline-based, fuel-gel mixture developed at Harvard University.

As opposed to the high-altitude precision bombing, which the Allies practiced with only mixed success over both Germany and Japan, incendiary raids were carried out at low altitudes of between 5,000 and 9,000 feet. The attackers were helped by the fact that Japanese air defenses were almost nonexistent by that point in the war. In fact, only 14 B-29s were lost in the March 9-10 Tokyo raid.

As was done in Europe, pathfinder planes flying ahead of the bombers marked the target with a flaming X, guiding the attackers in. Tokyo was hit over a three-hour period by three bomber streams that dropped roughly 2,000 tons of incendiaries near the docklands and in the industrial heart of the Japanese capital.

Tokyo immediately burst into flames. The combination of incendiaries, the way they were dropped, windy weather conditions and lack of coordinated firefighting on the ground resulted in a firestorm similar to what occurred two years previously in Hamburg, and only a month before in Dresden. Temperatures on the ground in Tokyo reached 1,800 degrees in some places.

The human carnage was appalling; bomber crews coming in near the tail end of the raid reported smelling the stench of charred human flesh as they passed over the burning capital.

Sixty-three percent of Tokyo's commercial area, and 18 percent of its industry, was destroyed. An estimated 267,000 buildings burned to the ground.

The firebombing campaign, coupled with the atomic bombings of Hiroshima and Nagasaki, are believed to have killed more than 1 million Japanese civilians between March and August of 1945.

Source: Various