Hackett saw active duty in the United States Marine Corps from 1989 to 1992, and then joined the Select Marine Corps Reserve. In 2004, he volunteered for active duty in the Iraq War, spending seven months as a civil affairs officer with the 4th Civil Affairs Group of the 1st Marine Division. He was assigned to Ramadi and supported the Fallujah campaign and reconstruction efforts there. On October 21, 2004, a convoy under his command was hit by two roadside bombs, but Hackett was uninjured. He returned to Ohio in early 2005.