September 1 marks the 75th anniversary of the start of World War II. In 1939, Germany invaded Poland. Denmark, Luxembourg, the Netherlands, Norway and Belgium soon came under German control, and when France fell less than a year later, Britain was the only nation left in Western Europe to oppose Adolf Hitler's Third Reich. Click through for key photos from the war.
On Thursday in Tampa, U.S. Secretary of Defense Chuck Hagel presided over a change of command ceremony during which Adm. William "Bill" McRaven handed over the reins of Special Operations Command to his successor, Gen. Joseph Votel.