General Arnold became alarmed at the situation and directed that his assistant, Major General B. E. Meyer, personally take charge of the entire modification program. The resulting burst of activity that took place between 10 March and 15 April 1944 came to be known as the "Battle of Kansas". Beginning in mid-March, technicians and specialists from the Boeing Wichita and Seattle factories were drafted into the modification centers to work around the clock to get the B-29s ready for combat. The mechanics often had to work outdoors in freezing weather. As a result of superhuman efforts on the part of all concerned, 150 B-29s had been handed over to the XX Bomber Command by 15 April 1944.