President Harry Truman made decision to drop the atomic bomb on Hiroshima because he

He chose to bomb Hiroshima because the other option of invading japan would lead to more bloodshed than the bomb itself could do.

it was also used to weaken their industries in Hiroshima and strong-arm the japanese into surrendering.

hope this helped a little

the effect of the ming leaders banning ships with more than two masts was that there was no further construction of ships masts, because there was a surplus. ming emperors disallowed foreign exploration