Major O’Connell was born on 28 May 1985 in Millis, Massachusetts. He holds an undergraduate degree in Criminal Justice from Western New England College and A Graduate Degree in Leadership from Boston University. He was commissioned in November 2008.
From 2009 to 2011 he served with Fifth Battalion, Tenth Marines at Camp Lejeune, NC where in his final billet he served as HQ Battery Commander. In 2010 he served as Battalion Fire Support Officer and Weapons Company Executive Officer to Second Battalion, Sixth Marines in support of Operation Enduring Freedom. In 2009 he served as Company Fire Support Officer to Company D, 2d Light Armored Reconnaissance Battalion in support of Operation Enduring Freedom. In 2010 he deployed with 2nd Battalion, 6th Marines as Artillery Liaison Officer and Weapons Company Executive Officer to Marjeh, Afghanistan in support of Operation Enduring Freedom. From 2011 to 2014, he was assigned to The Basic School in Quantico, VA where he served as a Warfighting Instructor, Staff Platoon Commander, BOC Executive Officer, and Instructor Education Program Officer. From 2014 to 2015, he was assigned as a student in the USMC Expeditionary Warfare School. From 2015 to 2017, he was assigned to First Battalion, Twelfth Marines in Kaneohe Bay, Hawaii where he served as Assistant Operations Officer and Commanding Officer, Headquarters and Charlie Battery. In 2016 he was part of forward deployed forces/UDP to Okinawa, Japan. From 2017-2018 he was a student in Marine Corps University’s Command and Staff College for AY18. From 2018-2020 he served as Faculty Advisor for conference group five at Marine Corps University’s Expeditionary Warfare School.
In August of 2020 Major O’Connell reported to 2d Battalion, 11th Marines to serve as 5th Marine Regiment Assistant Fire Support Coordinator. On 1 June 2021 he assumed the duties of Executive Officer for 2d Battalion, 11th Marines.