Enlisting as a flying cadet in February 1934, Edwinson took his flying training and continued as a flying cadet until February 29, 1936, when he was commissioned a second lieutenant in the Reserve, and assigned to Barksdale Field, Louisiana.
Going to England as a military observer with the Fighter Command of the Royal Air Force during the Battle of Britain, Edwinson returned to the United States in March 1942, to become group operations officer at Dale Mabry Field, Florida.