? You do realize that's exactly what happened, except months later and two cities full of schoolchildren burned - on top of the American dead. For example, when the battle of Okinawa was fought the US had been keeping its bomb secret for months, had everything needed for Hiroshima on hand, and had chosen its targets. Furthermore, the production of the Hiroshima bomb had been debugged, and more could be made rather easily and quickly (later, when an emergency came up, that was done - eight to ten Hiroshima weapons were produced in a couple of months after the war, starting from incomplete plans, for special purposes). The delay was for the Nagasaki design to catch up, so both could be dropped before any possible surrender. The battle of Okinawa was fought during that delay. Courage takes many forms - as does lack of same.