He entered military service in 1983, enlisting in the United States Marine Corp. as an infantryman. In 1987 he transferred to the Massachusetts Army National Guard. After attaining the rank of Staff Sergeant, he was selected to attend Officers Candidate School and in 1992 was commissioned an Infantry Second Lieutenant. He served as a rifle platoon leader and then rifle Company Commander.

In 1998 Captain Spellacy was order to Active Duty, as the Assistant Operations Officer for the then 1st Military Support Detachment (RAID) Team now known as the 1st Civil Support Team. In 2005, after being promoted to Major, he assumed the duties of Battalion Operations Officer and then Battalion Executive Officer for the 1st Battalion 182nd INF. He held that position during the unit’s deployment to Kosovo as part of the NATO peacekeeping force from 2006 to 2007.

LTC Spellacy has a degree in Political Science and has earned a Six Sigma Black Belt certification. He is currently pursuing a Master Degree in Emergency Management.

He awards include the US Army Meritorious Service Medal, the US Army Commendation Medal (5 awarded), Army Achievement Medal (4 awarded), NATO Campaign Medal, Kosovo Campaign Medal, the Global War on Terrorism Overseas Medal, the US Army Air Assault badge.