The Columbus exchange brought sickness for the natives which eliminated most of their population. This eliminated the chance of any form of a stand from them.
During the cold war, both leaders refrained from any physical or official acts of warfare. It mostly consisted of them taking control of foreign nations that were battling each other, but neither the US or Soviet Union declared war on one another. This was because it happened so soon after WWII that neither wanted to be held responsibly for another war.
During the 1943 invasion of Italy, General Eisenhower was a leading force who was behind the general invasion. He was an important force during the war who dictated how the American army was running the war in Italy.
