===Military aviation pioneer===Arnold immediately sent a letter requesting a transfer to the Signal Corps and on April 21, 1911, received Special Order 95, detailing him and 2nd Lt. Thomas DeWitt Milling of the 15th Cavalry, to Dayton, Ohio, for a course in flight instruction at the Wright brothers' aviation school at Simms Station, Ohio.
Junija 1909 je bil 29. pehotni polk premeščen v Fort Jay (New York), pri čemer je Arnold na poti v novo garnizijo v Parizu videl polet Louisa Blériota v njegovem prvem letalu.