Sergeant Major Smythe enlisted in the Marine Corps on 14 October 1987 and attended recruit training at Marine Corps Recruit Depot, San Diego, CA where he graduated a Lance Corporal. After completing the Motor Vehicle Operator's Course at Del Mar, Guantanamo Bay, Cuba in April 1988. In Cuba, he held billets as driver and dispatcher. In August 1988, he was promoted to Corporal and became the licensing MCO.
In April 1989, he received orders to 7th Motor Transport Battalion where he held billets as line NCO and driver. In August 1990, Corporal Smythe deployed to Saudi Arabia in support of OPERATIONS DESERT SHIELD/DESERT STORM.
In July of 1991, Corporal Smythe was ordered to Mare Island Naval Ship Yard to attend Marine Corps Security Forces School where he recieved orders to the Marine Detachment afloat, USS Abraham Lincoln. While serving aboard USS Abraham Lincoln, Corporal Smythe saw duty as Corporal of the Guard, Sergeant of the Guard and went ashore for operations in Somalia for OPERATION RESTORE HOPE.
In December of 1993, Sergeant Smythe reported to 1st Surveillance Reconnaissance Intelligence Group, where he made a lateral move to Corrections and attended the Corrections Specialist Course at Lackland Air Force Base, San Antonio, TX.
From August 1994 to August 1997 Sergeant Smythe served as an Assistant Section Leader and Section Leader at the Camp Pendleton Base Brig before being promoted to Staff Sergeant and transferring to the Joint Forces Brig, Okinawa, Japan where he spent 1997 to 2003 and held various billets as Duty Brig Supervisor, Training Chief and Chief Corrections Counselor. In January 2001, he was promoted to Gunnery Sergeant and saw the reopening of the Correctional Custody program in Okinawa where he held the billet of SNCOIC.
In June of 2003, Gunnery Sergeant Smythe received orders to Lackland Air Force Base, San Antonio, TX to be an instructor at the Corrections Specialist Course. While in Texas, he served as Instructor and Detachment Gunnery Sergeant.
In February of 2006, Gunnery Sergeant Smythe was promoted to First Sergeant and ordered to 1st Combat Engineer Battalion where he deployed to Iraq with Charlie Company in 2007 and to Afghanistan with Delta Company in 2009. In April 2010, he was promoted and assigned as Squadron Sergeant Major for Marine Heavy Helicopter 462 Miramar, California. In Feburary 2012 he reported to 3d Battalion 12th Marines and assumed his present duties as Battalion Sergeant Major.
Sergeant Major Smythe's personal awards include the Meritorious Service Medal, Navy and Marine Corps Commendation Medal with two gold stars in lieu of third award, Navy and Marine Corps Achievement Medal with one gold star in lieu of second award, the Outstanding Volunteer Medal, and the Combat Action Ribbon.