three o'clock
`` By twos , follow Cadet Herbert inside and he 'll assign you to your quarters . Shower , shave if you have to and can find anything to shave , and dress in the uniform that 'll be supplied you . Be ready to take the Academy oath at '' -- he paused and glanced at the senior cadet who held up three fingers -- `` fifteen hundred hours . That 's three o'clock . All clear ? Blast off ! '' Just as the boys began to move , there was a sudden blasting roar in the distance .