The French and Indian War was the longest US war before 1850.The longest US war in history was the Vietnam War.
The war on drugs
Yes but not caused by the us.
If you mean only involving the US, than the Civil War.
The longest war the United States ever entered was the Vietnam War.
The first official battle of World War II involving overt US military presence was the Battle of Pearl Harbor.
Viet Nam 1961-1975
The US has been fighting in Afghanistan longer it was fighting in Vietnam. It is the longest war in US history.
Vietnam
we ate poopsicles for months after world war two
The unexpected turn of events that occurred in postwar Vietnam involving the US was the refugees. A refugee is someone who leaves their country because of a war.
We were fighting ourselves during the US Civil War (1861-1865), so that may have been the deadliest.