Why didn't the U.S. soldiers win the vietnam war

Simply put, they were fighting an unpopular war that was against an enemy we basically couldn't see. We were fighting an enemy who would hide among the Vietnamese civilians. Many of the soldiers we were fighting were untrained farmers, however the fact they would not come out as soldier made it harder to root them out. They also knew the land better than us so they had the terrain to their advantage. The Vietnamese were just guerilla fighters, who we had issues with fighting because we could never tell who was an enemy. Often times, civilians would die due to the choices of these fighters, causing the Vietnam war to be very unpopular back at home. So our soldiers who had no morale to boost them back at home, were fighting an invisible enemy and then coming back home and being booed fr what thy did.

europeans, particularly with the first conquistadores of the iberian explorations, was to insert into the american biosphere new diseases, such as smallpox, measles, etc, that the native americans had no resistance to (unlike eurasians and africans, who by natural selection if nothing else, had developed some genetic resistance to those diseases).

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