Franklin Delano Roosevelt might be America’s greatest 20th century president, but there’s no question that he was the most unique. A well-connected relative of Theodore Roosevelt, FDR was groomed for greatness until he was struck down by polio. Nevertheless, he persevered, rising through New York politics to reach the White House just as the country faced its greatest challenge since the Civil War, beginning his presidency with one of the most iconic lines ever spoken during an inaugural address. For over a decade, President Roosevelt threw everything he had at the Great Depression, and then threw everything the country had at the Axis powers during World War II. Ultimately, he succumbed to illness in the middle of his fourth term, just before the Allies won the war.

Among America’s presidents, Harry Truman’s presidency produced some of the nation’s most crucial decisions and left one of the nation’s most unique legacies. When President Franklin Roosevelt died in April 1945, Vice President Truman, somewhat unprepared for the Presidency, now had to fill some of the biggest shoes in American history. Incredibly, Truman had not been informed of the country’s secret attempt to build atomic bombs.

The new president had to usher America through victory in Europe in his first month and decide to drop atomic bombs on Hiroshima and Nagasaki a few months later, but the end of World War II produced only the first of many consequential decisions Truman would face during his nearly 8 years in office. As president, Truman would lay the groundwork for the next 50 years of American foreign policy, as the architect of Cold War containment, the man who signed off on the Marshall Plan, and the commander-in-chief during much of the Korean War.