AuCoin enrolled at Pacific University in Forest Grove, Oregon, then transferred to Portland State University. In 1961, he enlisted in the United States Army. He was assigned to the 2nd Infantry Division and the 10th Mountain Division where he served as a public information specialist, writing dispatches to "The Nashville Banner", the Louisville "Courier-Journal", The Nashville "Tennessean", "Stars and Stripes", and "Army Times", among other publications. AuCoin's Army postings included Fort Ord, California; Fort Slocum, New York; Fort Campbell, Kentucky; Fort Benning, Georgia; and Sullivan Barracks, West Germany. While stationed in the segregated South, AuCoin was caught up in a near race riot in reaction to a sit-in by blacks at an all-white lunch counter, an event that crystallized his zeal for progressive politics.