No war is necessary. But, this was a war over rejoining the Union. So maybe it was.
The Canadians persuaded many Americans that a war with spain was necessary.
Buying only products necessary to live
It started as a skirmish on a disputed no man's land where Americans died. This was used as a pretext to start the war. The real reason of the war was to acquire California by all means necessary.
The American civil war.
More Americans were lost than in any other war. And Americans were fighting Americans.
Some problems Americans faced were not knowing the correct amount and support which was required by an army. They had no staff officers within the militia of any colony.
The Americans lost the Vietnam War (1954-1975).
To have more space
As necessary as the cold war was....so yes
One measure President Woodrow Wilson did to prepare for war was by convincing Americans that war was necessary using the Committee of Public Information. He also increased the size of the US Army to 400,000 in 1915.
The revolutionary war.
No war is necessary. But, this was a war over rejoining the Union. So maybe it was.