What crucial mistake did British general Cornwallis make that contributed most directly to the defeat of the British army?

He disregarded an order and returned to Yorktown Peninsula.

Explanation:

What crucial mistake did British General Cornwallis make that led to the defeat of the British army? He disregarded an order and returned to Yorktown Peninsula.

Explanation:

a big wall across the mexican border so no drugs, terrorist, or illegal immigrants can come through : )    

yes.

explanation:

because it let the japanese know who had the upper hand in the war.