The first B-29 bombing raid from India took place on 5 June 1944. Ninety-eight B-29s took off from bases in eastern India to attack the Makasan railroad yards at Bangkok, Thailand. Bombardment operations against Japan were planned to be carried out from bases in China. There were four sites in the Chengtu area of China that were assigned to the B-29 operation—at Kwanghan, Kuinglai, Hsinching, and Pengshan. The primary flaw in the Operation Matterhorn plan was the fact that all the supplies of fuel, bombs, and spares needed to support the forward bases in China had to be flown in from India over the Hump, since Japanese control of the seas around the Chinese coast made seaborne supply of China impossible.