Born soon after America's entry into the First World War, John Fitzgerald Kennedy was the nation's first President born in the 20th century. Both parents were from wealthy Boston families with long political histories. His maternal grandfather had been mayor of Boston. Kennedy's father, Joseph P. Kennedy, had made a fortune in the stock market, entertainment, and other business, managing to take his money out of the stock market just before the crash of 1929. Though the ensuing Great Depression gripped the nation, "Jack" and his eight siblings enjoyed a privileged childhood of elite private schools, sailboats, servants, and summer homes. Kennedy later claimed that the only experience he had of the Great Depression was what he read in books while attending Harvard University. For John, this privileged childhood was interrupted repeatedly by chronic bouts of illness. Afflicted with an almost constrain stream of ailments, several of which went undiagnosed, Kennedy spent much of his time recuperating. In 1938, on the eve of the Second World War, President Franklin D. Roosevelt appointed Joseph P. Kennedy, John's father, to the key post of ambassador to the United Kingdom. The new ambassador was unsympathetic to British preparedness policies and found a cool reception in London. That year, Jack inherited one million dollars from his family, but his ambition remained strong. While in England with his father, he wrote his senior essay for Harvard University on England's lack of readiness for the Second World War. It was published and was well received by critics, becoming a bestseller under the title Why England Slept. World War II Military Service After Kennedy graduated from Harvard, the United States entered World War II. His efforts to join the U.S. Navy were initially thwarted by his ill-health, but through the intervention of his father, he was eventually admitted and assigned to serve in the South Pacific, commanding a small motor-torpedo boat, or "PT boat." Kennedy and his crew participated in the campaign to wrest thousands of islands from Japanese control. In August 1943, as the sailors were sleeping without posting a watch (in violation of naval regulations), his boat, PT 109, was rammed by a Japanese destroyer. Towing a badly burned crewmate by a life-jacket strap clenched in his teeth, Kennedy led the crew's ten survivors on a three-mile swim to refuge on a tiny island. The crew hid on the island from the enemy for days until Kennedy managed to summon help. Widely credited with the rescue of his crew, Kennedy received the U.S. Navy and Marine Corps Medal for Valor, and a Purple Heart for injuries he sustained. Nevertheless, he returned home to a naval inquiry on the sinking. Although a board found evidence of poor seamanship, the Navy needed heroes more than it needed scapegoats, and Kennedy was cast as the former to build public morale, and recruited to go on speaking tours. The war ended in 1945, but not without a deep cost to the Kennedy family: the oldest son, Joseph Jr., a pilot, was killed on a bombing mission in Europe. Handsome and outgoing, Joseph had been the one tabbed by his father to become President one day. Upon his death, his father's aspirations fell on John.