Lieutenant-Colonel McGarry enrolled in the Canadian Forces in June 1988. He began his career at the Royal Military College of Canada in Kingston, Ontario, and graduated with a Bachelor of Arts (Commerce) degree in 1992. On commissioning, LCol McGarry was posted to regimental duty with the 1st Regiment Royal Canadian Horse Artillery in Shilo, Manitoba. His initial regimental tour included service with B Battery (1992-1993) and A Battery (1993-1997). During this period he spent 6 months as the personal assistant to Commander 1 CMBG and also deployed to Bosnia on Operation PALLADIUM as a forward air controller.
In July 1997, LCol McGarry was posted to 11th Field Regiment in Guelph, Ontario as the training officer and in 1998 assumed command of 11 (Hamilton-Wentworth) Battery, in Hamilton, Ontario. After being posted to Kingston in 1999, LCol McGarry completed the Land Force Technical Staff Course in 2000 and was subsequently posted to the Land Force Doctrine and Training System HQ until 2001.
In July 2001, LCol McGarry returned to the 1st Regiment in the capacity of BK B Battery and became the Operations Officer in June 2002, a position he held until the summer of 2003. LCol McGarry also deployed with 1 RCHA as part Operation GRIZZLY during the 2002 G8 Summit in Kananaskis Valley, Alberta. In May 2003, he was promoted to Major and appointed G3 of Canadian Forces Base Shilo. Following this staff tour, LCol McGarry was selected to command C Battery, 1RCHA and spent one year with the 1st Regiment supporting 3rd Battalion, Princess Patricia’s Canadian Light Infantry.
LCol McGarry relinquished command of C Battery in 2005 and took over as the Second-in-Command for 1 RCHA, a position he held until the summer of 2007 when he proceeded to the Canadian Forces College to attend the Joint Command and Staff Programme. Upon graduation LCol McGarry was posted to the Canadian Forces Language School for second language training, where he served until selected to Command 2 RCHA in 2009.
Lieutenant-Colonel McGarry and his wife Tammy are the proud parents of Cassandra and Kyle.