GySgt Petersen joined the Marine Corps in July 1999 and went to bootcamp in January 18, 2000.  He graduated from Marine Corps Recruit Depot, San Diego April 14, 2000 where he then reported to Infantry Training Battalion, School of Infantry-West, Camp Pendleton, California. 

On July 14 2000, Private First Class Petersen reported to 1^st Battalion, 1^st Marine Regiment, 1^st Marine Division as a Rifleman. In 2001, LCpl Petersen deployed on a WestPac with the 15^th Marine Expeditionary Unit.   October 2001 LCpl Petersen deployed to Pakistan and Afghanistan in support of Operation Enduring Freedom.  He was assigned as a SAW gunner in 2^nd Platoon Charlie Company, 1^st Battalion, 1^st Marine Regiment, 1^st Marine Division. Upon return from the deployment, Cpl Petersen served as a fire team leader.  In October 2003, Sgt Petersen served as a squad leader in Kilo Company, 3^rd Battalion, 1^st Regiment, 1^st Marine Division.

In 2004, Sgt Petersen reported to Headquarters Company, Mobilization Command in Kansas City as a training NCO and conducted training in support of Marine Force Reserve. In 2008, Sgt Petersen reported to IMEF, Advisor Training Company at a platoon Sergeant for MiTT (Military Training Team) 472 and deployed to Iraq in support of Operation Iraqi Freedom.  After returning from the deployment, SSgt Petersen left active duty.

In June 2017, SSgt Petersen reenlisted as an off-contract accession to the Marine Corps Reserves as a Platoon Leader for AT TOW Training Company in Tulsa, Oklahoma. 

 SSgt Petersen came on the Active Reserve program and reported to Prior Service Recruiting Basic Course in 2018 and was assigned to PSPCS Joliet, IL. SSgt Petersen submitted an 8422 package and became the SNCOIC of PSRSS Kansas City, 9^th Marine Corps District.

In July 2023, GySgt Petersen was slated to become the Operations Chief for 1stMCD PSR.

GySgt Petersen’s awards include Navy and Marine Corps Commendation Medal, 3 Certificate of Commendation, and a Certificate of Appreciation.