Tokyo was bombed repeatedly after November 1944 as the Americans opened air bases in the Mariana Islands that were in range. The most stunning results came on the night of March 9–10, 1945. The U.S. Army Air Forces sent 325 B-29s over Tokyo. They came in at low level and were unescorted because the Japanese air defense system was totally inadequate. They dropped 1665 tons of incendiary bombs containing a jelly-like mixture of rubber, lye, and coconut oil, all blended with gasoline. An unstoppable conflagration burned out 45 square kilometers and killed over 100,000 people in a matter of minutes. Most of the victims suffocated in bomb shelters when the raging fires consumed the oxygen. One fourth of the buildings in the entire city were destroyed. The raid marked a turning point in the American strategic air war against Japan. Previously, most methods were "precision" raids that used high explosives against industrial targets. Now, the strategy was to use area raids that used incendiary bombs to burn Japanese cities and kill the workers who kept the war machine going. Leaflets were dropped by the millions to order civilians to evacuate to the towns and rural areas which were not bombed. Half of Tokyo's 7.4 million residents did flee. The strategy was similar to the air war against German cities and reflected prewar Air Force strategic planning, which focused on the burning of Tokyo and other industrial and command centers as a way to destroy the enemy's military capability.