In the beginning, as the senior trade in the branch, the Armourer trade started when the first stone axe or the stone headed club was made.

Although it was many years till we were officially recognized. This happened during the reign of Henry I / Henry II in 1181 when they appointed someone to provide maintenance to the equipment held by the army. He was also recognized the need for someone to be responsible for the soldiers’ equipment and weapons.

Approximately 100 years later an Attillator was appointed to maintain and provide, "Engines of War", these were such things as slings, battering rams, etc…

With the invention of the cannon in approximately 1300 AD increased the worth of this official who became known as the Master of Works, Engines, Cannons and other kinds of ordnance for war. In 1414, the title "Master of Ordnance" was introduced. The Armourers were given their charter in 1435, although it was know that they had been in existence for some 300 years.

In 1660, a Master General of Ordnance was appointed to oversee the setting up of government arsenals, factories for the manufacture of small arms and guns. These arsenals were taken over by the ordnance board and were supervised by the inspector of small arms.

In 1858, the Corps Armourer Sergeants were formed to carry our repairs to small arms, machine guns, and guns. This proved to be too much for the small group of men to do and in 1882, the Corps of Artificers was formed to repair the artillery equipment (guns). The two Corps were joined together and became the Ordnance Store Corps.

Later in 1896, the Ordnance Store Corps became the Army Ordnance Corps of which the Armourers and the Armament Artificers were the principal technical tradesmen in the Army.

Armourers and Artificers have been involved in every battlefield since the conception of weapons. Some of these battles were as follows: Crimean War (1856 – 1858), this is where the ordnance was to provide a siege train which would cater to the Artillery and Engineers requirements. World War I, during this period the Ordnance Corps was extremely busy as there were no real stocks of anything, not even small arms or machine guns. The Armourers were busy repairing, inspecting, maintaining and generally patching up the unhappy tales of hundreds of different marks of the Ross rifles in service at that time. For the Artillery Artificers, the guns in battle were used primarily to cut holes in the hundreds of miles of barbed wire in front of the enemy trenches. In some cases, the guns were firing in excess of 1000 rounds a day. The problem of keeping prewar guns dating back to 1903 in daily operation may be imagined when it was noted that one gun had fired 21,000 rounds before being condemned. World War II (1939 – 1945), the Armourers and the Artillery Artificers were back at work once again. The British Army on advice of the Breveridge report created a grouping of tradesmen called the Royal Electrical Mechanical Engineers (REME) in 1942. With great pressure, Canada followed in 1943 with the Canadian Corps of Electrical Mechanical Engineers (CCEME). In 1944, "Royal" was added and the Corps became known as the Royal Canadian Electrical Mechanical Engineers (RCEME)

Post war period, with the advent of integration trade structure policy, in 1968, the Armourers and the Artillery Artificers became one trade, Weapons Technician Land MOC 421. These men were to take the responsibility for all land weapons, revolvers to artillery pieces. Weapons technicians are responsible for all weapons maintenance and are able to plan, organize, conduct and supervise maintenance programs for all weapons and related ancillary equipment. Weapons technicians are employed at all lines of maintenance, instructional positions and throughout the world with the Canadian Armed Forces. MOC 421 has approx 400 serving members at this time.