Where was the first confirmed outbreak of the Spanish flu pandemic of 1918-1920?

Surprisingly, the first confirmed outbreak was at Camp Funston, an American military base in Fort Riley, Kansas, which was training American soldiers to fight in World War I. Studies by a British team of virologists in 1999 have shown that in retrospect, the disease could be found in 1917 (though never identified as such), at a military base in Etaples, France, which was a staging area for the war, and in which perhaps a 100,000 troops passed through everyday. The base was identified as "ground zero".

By August of 1919 a more virulent form of the flu was identified in Boston, Massachusetts, Sierra Leone, Africa, and Brest, France. The disease was called Spanish Flu because it received greater publicity after moving from France to Spain late in 1919. It has been called "the greatest medical holocaust in history", (though some believe the "Black Death" has that dishonor), ultimately killing from 50 to 100 million people worldwide, including between 500,000 and 675,000 in the US and perhaps 250,000 in Great Britain.