John F. Kennedy was born in 1917, just as the United States entered World War I. By the time of JFK's birth, the U.S. had demonstrated an undeniable interest in international affairs, and the fact that U.S. intervention helped shaped the course of World War I cemented the status of the U.S. as a world power. JFK's formative years spanned the 1920s, a period of booming prosperity in the U.S. that became known as the "Roaring Twenties." The economic boom came to an abrupt end, however, with the stock market crash of 1929. The subsequent economic collapse was partially alleviated by President Franklin Delano Roosevelt's "New Deal;" in Europe, however, it led to the collapse of Germany's democratic government, and the rise to power of Adolf Hitler.
Under Hitler and his Nazi-run government, Germany gradually absorbed its weaker neighbors, while Britain (where JFK's father, Joseph Kennedy, Sr. was the American ambassador) and France attempted to appease the Nazis rather than fight them. Eventually, however, German aggression provoked World War II (1939-1945). The U.S. was sucked into the conflict when Japan, Hitler's ally, bombed the American naval base at Pearl Harbor on December 7, 1941. World War II, in which JFK became a hero and his brother Joe Jr. was killed, ended with Germany defeated, Europe prostrate, and the United States and the Soviet Union as the world's two "superpowers."
The "hot war" of World War II soon gave way to the Cold War, the decades-long duel between the U.S. and the U.S.S.R. for global dominance. Franklin Delano Roosevelt died in 1945, at the beginning of his unprecedented fourth term in office, and Harry Truman became president. He was reelected in 1948, and during his second term, the U.S. became involved in the Korean War (1950-1953), during which American troops helped fend off an invasion of South Korea by Soviet-backed North Korea. At home, Senator Joseph McCarthy began his investigations into Communist infiltration of the State Department, the movie industry, and various other domains of American life. While there were, as recent Cold War scholarship has shown, many Soviet spies in the U.S. during this period, McCarthy's paranoia-fueled crusade led to an overzealous witch-hunt mentality that persisted until his downfall in 1954.
By that point, former general Dwight Eisenhower had become president, having defeated Democrat Adlai Stevenson in the 1952 election. Eisenhower's hands-off style and fatherly demeanor made him one of America's most popular presidents, and he presided over an era of prosperity at home and cautious dueling with the Soviet Union abroad. But beneath the placid surface, the seeds of later turmoil were being sown. The Civil Rights Movement got under way in the 1950s, with school integration and sit-ins to protest segregation all across the South. By the end of Eisenhower's second term, meanwhile, many Democrats accused the administration of having allowed U.S. foreign policy to drift, while Soviet power increased.
Running for president in 1960 against Eisenhower's Vice-President, Richard Nixon, JFK was able to exploit these fears and win the election. With his ringing inaugural declarations that the U.S. would "pay any price" and "bear any burden" in the struggle against Soviet tyranny, JFK explicitly opened a new, more bellicose phase of the Cold War, one that would culminate in the most dangerous event of his presidency, the Cuban Missile Crisis. On the domestic front, the rising tide of civil rights protest erupted in the early years of his presidency, forcing him to send federal troops into a number of southern states. Finally, a principal component of U.S. Cold War policy–American involvement in the former French colony of Vietnam–began to demand a larger share of political attention and resources in the early 1960s, paving the way for full-fledged military intervention in what came to be known as the Vietnam War. JFK's presidency signaled the end of the tranquil Eisenhower years and the turbulence of the 1960s that was waiting in the wings.