In its early years the unit helped Ottawa deal with emergencies and stage public ceremonies.
During the First World War, 181 of its members received 26 decorations serving with units of the Canadian Expeditionary Force.
On the outbreak of the Second World War, 3rd Field Company, RCE was mobilized as part of the First Canadian Division Engineers and embarked for Scotland.
As the Canadians fought through Sicily, Italy, then France and Holland, the Engineers reconnoitered the ground over which the armies advanced, crossed rivers, built roads and bridges, located and disarmed mines and booby-traps, built communications networks and constructed field defences.
In peacetime, 33 CER trains to conduct demolitions, water supply, bridging, route maintenance, obstacle emplacement, mine awareness and geomatics/mapping support.
Notes: The 5th Field Company, CE was authorized a Reserve order of battle counterpart on 15 June 1920 (GO 89/20 and GO 128/30).
The company participated on the landings at Spitzbergen in August 1941, and in Sicily in July and Italy in September 1943 as part of the 1st Canadian Infantry Division.
The unit landed in France in March 1945 on its way to the North West Europe theatre of operations in which it served until the end of the war.
The company landed at Normandy as part of First Canadian Army Troops in June 1944 and continued service in the North West Europe theatre of operations until the end of the war.