He was responsible for managing the affairs of the Florida Military Department and for advising the Governor, who is the Commander-in-Chief of the Guard.

General Calhoun deployed with the 50th ASG in 2003 as Director of Host Nations Support during Operation Iraqi Freedom and served as Deputy Commander, Task Force (FL) in Mississippi during Hurricane Katrina.

In the years since his enlistment in the Army as a private in 1977, his duties have ranged from providing first aid to Cubans arriving in Florida during the 1980 Mariel boatlift, to spending a year deployed with a combat support unit in Kuwait after the American invasion of Iraq.

In that position, MG Calhoun was responsible for the operations and has command over all aspects of the Florida Army and Air National Guard.

He also received a master's degree in Strategic Studies from the United States Army War College.