Greg Touhill was commissioned a 2d Lt through the Air Force ROTC program at Pennsylvania State University on May 28, 1983. He attended the Basic Communications-Electronics Officer Course at Keesler AFB, Mississippi, from October 1983 to May 1984, and then served as a Maintenance Control Officer and Chief of Quality Assurance with the 25th Air Division at McChord AFB, Washington, from June 1984 to May 1987. Capt Touhill next served as Chief of Maintenance for the Northwest Air Defense Sector at McChord from May to December 1987, followed by service as Chief of Operations and then Commander of the 2160th Communications Squadron at RAF Fairford, England, from January 1988 to October 1990. He was Deputy Commander of the 7020th Air Base Squadron at RAF Fairford from October 1990 to February 1991, and he then attended the Advanced Communications-Computer Officer Training Course at Keesler before serving as Chief of Command and Control Computer Resources with Headquarters Strategic Air Command at Offutt AFB, Nebraska, from August 1991 to February 1992. His next assignment was as Executive Officer of the 1st Aerospace Communications Group at Offutt from February 1992 to March 1993, followed by a deployment to Southwest Asia as a Systems Flight Commander with the 4404th Communications Squadron from March to June 1993. Maj Touhill attended Air Command and Staff College at Maxwell AFB, Alabama, from July 1993 to June 1994, and then Armed Forces Staff College at Norfolk, Virginia, from June to September 1994. He then returned to Offutt as a Communications Staff Officer with U.S. Strategic Command from September 1994 to March 1997, followed by service as Commander of the 77th Communications Squadron at McClellan AFB, California, from March 1997 to July 1998. Col Touhill attended Air War College at Maxwell AFB from July 1998 to June 1999, and then became Chief of the Transmission Systems Branch with the Air Force Communications and Information Center in Washington, D.C., where he served until February 2000. He served with Headquarters U.S. Air Force in the Pentagon from February 2000 to June 2001, and then became Commander of the Air Mobility Command Communications Group at Scott AFB, Illinois, from July 2001 to July 2003. Col Touhill was Director of Personnel Data Systems with Headquarters Air Force Personnel Center at Randolph AFB, Texas, from July 2003 to May 2005, and he then deployed to Southwest Asia, where he served as Director of Command, Control, Communications and Computer Systems with U.S. Central Command Air Force in the Combined Air Operations Center until June 2006. He then returned to Scott AFB as Director of Communications from June 2006 to October 2007, before serving as Commander of the 81st Training Wing at Keesler AFB from October 2007 to April 2009. Gen Touhill next served as Chief of the Office of Military Cooperation at the U.S. Embassy in Kuwait from May 2009 to June 2011, followed by service as Director of Command, Control, Communications and Computer Systems with U.S. Transportation Command at Scott AFB from June 2011 until his retirement from the Air Force on July 1, 2013. Gen Touhill won the Air Force Communications-Computer Systems Professional Achievement Award for 1986, 1988, and 1989, as well as the Air Force Science and Engineering Award for Engineering Achievement in 2006.

His Bronze Star Medal Citation reads:

Colonel Gregory J. Touhill distinguished himself by meritorious service as Director, Command, Control, Communications and Computer Systems, United States Central Command Air Forces, Combined Air Operations Center while engaged in ground operations against the enemy at Al Udeid Air Base, Qatar from 10 May 2005 to 13 May 2006. During this period, Colonel Touhill's strong leadership, combat focus and strategic vision were instrumental to the success of Operations ENDURING FREEDOM, IRAQI FREEDOM and Joint Task Force HORN OF AFRICA. Colonel Touhill led the command's one billions-dollar communications network, directing 1,500 personnel at 21 locations in 12 countries to provide positive command and control of coalition forces. On numerous occasions, he forward deployed to combat locations in Iraq, leading creation of a transformational communications system which received praise from the Secretary of the Air Force for providing lifesaving persistent, reliable radio communications to convoys along main supply routes. As architect of the Air Defense of Baghdad command and control network, he fused military and air traffic control radars into an integrated sensor network which proved vital to positive airspace control during the historic Iraqi national elections. Deploying into the Afghanistan theater of operations, Colonel Touhill directed improvements to the fighter aircraft communications extension pod system, which raised the reliability of close air support communications from 35 to over 99 percent effectiveness. The exemplary leadership, personal endeavor, and devotion to duty displayed by Colonel Touhill in this responsible position reflect great credit upon himself and the United States Air Force.