On June 27th, 1950, in order to assist non-Communist forces on the Korean peninsula, President Harry Truman sent U.S. troops to help push back the Communists who had invaded South Korea.

On August 6th and August 9th of 1945, the U.S. dropped an atomic bomb on Hiroshima and Nagasaki, resulting in the Japanese surrender of World War II.

In 1962, President Kennedy ordered the naval blockade of Cuba which many believe pushed the USA and the USSR perilously close to conflict, until the Soviet Union eventually withdrew.

The U.S. invaded Caribbean nation of Grenada in response to the coup orchestrated by a Marxist faction within the Grenadine government.

Franklin Roosevelt signed the Lend-Lease Act in May of 1941, shortly after Nazi Germany began occupying France. Support for the Allied cause had been increasing among the American public throughout the preceeding year. The Lend-Lease Act was the first offical support for the Allied cause from the American government, in the form of direct lending of war materiel. The program continued throughout the war, even after the United States officially entered combat on the Allied side.

The Civil War saw a peculiar nature to its naval battles, as the Union held a firm blockade around all Southern ports, and held more ships. Nonetheless, a consistent fleet of small "blockade runners" allowed the Confederacy to keep the U.S. Navy busy throughout the war. In 1862, the Confederacy acquired a stranded U.S. vessel, the Merrimack, gave it an iron plate shell and battering ram, and rechristened it the Virginia. This new "ironside" wreaked havoc for a few months, until the U.S. developed the all iron Monitor, which then sought out its iron counterpart. Their naval battle on March 8, 1862 at Hampton Roads, VA, proved a loud and famous draw, but also showed that the era of wooden sailing ships was over.

Planes first became usable after the Wright Brothers' flight in 1903, and were instantly sought for military use. By World War I, all the major countries involved were using planes as military weapons in a number of ways. Despite America also using planes in World War I, the pilots were member of the Army, specifically the Air Corps. This model held until the Second World War, when an increased use of planes showed a need for better organization of their use. In the National Security Act of 1947, the United States Air Force was officially created as a separate branch of the armed forces.

The Pacific Theater was one of the largest extended battlefields in world history. Primarily fought between the United States and the Empire of Japan, as their European allies were occupied in Europe, the battles in the Pacific were largely naval, and in particular featured a great number of aircraft carriers and airplanes, rather than infantry engagements or even tank battles. The Pacific Theater of the war ended fighting when the U.S. dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki, the first use of nuclear weapons.

The phrase "peace with honor" became famous almost immediately after the Vietnam War ended. President Richard Nixon first spoke it in an address to the nation upon the offical signing of the Paris Peace Accords, which ended the Vietnam War. The highly controversial war became a key element of the 1972 Election, with Nixon eventually promising to end the war as soon as possible. On January 23, 1973, shortly after being inaugurated for a second term, Nixon uttered these words to the nation to let them know he had negotiated a peace with North Vietnam.

From 1948, when the State of Israel was first established, until 1978, four large scale wars occurred between Israel and various Arab alliances, typically led by Egypt. By the 1970s, with Cold War tensions driving foreign policy decisions, American leaders sought a deeper peace in the Middle East. In 1977, President Carter invited Egyptian President Anwar Sadat and Israeli Prime Minister Menachem Begin to Camp David in Maryland. There, Carter helped negotiate a framework for a peace agreement between the two nations.