Lieutenant-Colonel (LCol) MacLellan joined the Canadian Armed Forces (CAF) under the Regular Officer Training Plan (ROTP) program, with a scholarship to attend Saint Mary’s University in Halifax, Nova Scotia.In 2007, LCol MacLellan was posted to the Director of Information Management, Technology, Products, and Services (DIMTPS), employed as the site installation coordinator on the Global Defense Network Services (GDNS) transition team and as the National Switched Voice Services Manager. In 2009 he was posted to the Canadian Forces School of Communication and Electronics (CFSCE), first employed as an instructor in 1 Squadron, focusing on DP 1 Signals Officer training, and in 2011 he moved into the 1 Squadron Second in Command position. In 2012 he was posted to the Canadian Forces Joint Signal Regiment (CFJSR) as the Regimental Plans Captain and in 2013 assumed the role of Adjutant at the CFJSR. Upon completion of second language training in 2015, LCol MacLellan returned to CFJSR as the Regimental Operations Officer. In July 2016, LCol MacLellan was posted to the Canadian Joint Operations Command (CJOC) Headquarters in the J6 Capability Integration (CI) cell. His main role was to enable the institutionalization of the Canadian Deployable Mission Networking (CDMN) capability. In 2018, he was appointed Officer Commanding 4 Squadron, 77 Line Regiment. In 2020, he was posted to the Directorate of Land Command Systems Program Management (DLCSPM) as the Chief of Staff. In 2023, he was posted to Canadian Army Headquarters as Director Land Requirements 4 (C4I and EW Systems). In 2024, LCol MacLellan was appointed Commanding Officer of CJOC Headquarters in Ottawa.LCol MacLellan is a graduate of the Joint Command and Staff Programme at the Canadian Forces College. He holds a Bachelor of Science and Diploma of Engineering from Saint Mary’s University, and a Master of Business Administration from the Royal Military College of Canada.LCol MacLellan deployed as part of RC South HQ in Kandahar, Afghanistan from 1 September 2008 – 1 March 2009 as SO2 Visits.