The German "u-boat" aka the Submarine was highly effective due to having the element of underwater travel. This way, they could sneakily send missiles at other naval ships without risk of detection. These days, submarines are an essential part of naval force, and underwater detection systems are being created in order to detect these more often.
Manifest Destiny supporters would be in favor of D acquiring land west of the Mississippi river. Manifest Destiny is the belief that America should take land from the Atlantic to the Pacific ocean.
