3rd Amendment (Full Text)
"No soldier shall, in time of peace be quartered in any house, without the consent of the owner, nor in time of war, but in a manner to be prescribed by law."

If war was to set foot on American soil, then soldier generals and government officials may try to force American citizens to house soldiers due to lack of quarters. Under the constitiuiton, we would be protected from this. We would not have to give up any space we need for the soldiers.