The response of the US government to the declaration of war against Germany in April 1917 was astonishingly rapid. Virtually overnight, 4 Million men were drafted, and military contracts handed out to every likely contributor to the war effort, including the motorcycle industry. By 1917, after the ‘terrible ‘Teens’ leveled the majority of American motorcycle factories (due to rising material and labor costs), only the Big 3 (Excelsior-Henderson, Indian, and Harley-Davidson) were able to supply motorcycles in large quantities required. Smaller brands also supplied machines (like Cleveland’s little two-stroke single) in miniscule quantities.The Excelsior and Henderson brands had both been incorporated under Ignaz Schwinn’s two-wheeled Chicago empire by October 1917 (read ‘The Big X and the Big 3’ for more) but at the start of the war only Excelsior was under Schwinn’s control. The Henderson Motorcycle Co. was struggling with a red balance sheet and was unable to capitalize on military contracts to stay afloat a few more years, although after the Schwinn takeover a few Henderson 4s were adopted for military use. When US inspectors documented the factory and testing regime at Schwinn’s Chicago factory, only Excelsior v-twins were built there, and these are the machines documented in the National Archive.These photographs – to the best of our knowledge – have never been published previously (except in our Excelsior-Henderson story here), and document mostly the testing regime of the day: find a nasty place to ride, and have at it! Excelsior V-twins are very tough motorcycles, and were faster than both their Indian and Harley-Davidson rivals in 1917/18 in production form, so would have been the bike to have in WW1! While the British rode Douglas, Triumph, and Trump singles and v-twins, an Excelsior of this era would have walked away from them all. Enjoy the photo series!