President Truman had a very difficult decision to make in terms of dropping the atomic bomb. Before dropping the bomb, Truman was hoping to get an unconditional surrender from Japan after the demands made at the Potsdam Conference. However, Japan refused.
Instead of dropping the atomic bomb, he also considered an invasion of mainland Japan. However, this invasion was estimated to have millions of casualties total and would have resulted in the deaths of thousands of Allied forces and Japanese military personnel.
Ultimately Truman decides to drop bombs on Hiroshima and Nagasaki, effectively ending World War II. Even though this was a weapon of massive destruction, he argued that this actually saved lives. He used the estimated number of deaths/casualties from the possible land invasion to justify his decision.
1. It led congress to replace their military with an all volunteer one and made them decrease the voting age to 18.
2. Since President Johnson who was president at the time, refused to raise takes we had cycles of inflations occur.
3. Because of the war, it sparked widespread distrust of the U.S government since it a lot of people thought that they shouldn't have gotten involved and that it was completely horrific. It also made the U.S military less popular.
I believe it was Spain. they were the ones who discovered a lot during that time period.