The Regiment, with a strength of two squadrons, moved in August 1914 from Toronto and St. Jean, PQ to Valcartier, PQ where C Squadron was formed. LCol C.M. Nelles took the Regiment overseas on the 3 October 1914 to England where intensive field training was undertaken at Maresfield. The Regiment then became part of the Canadian Cavalry Brigade commanded by Brigadier General Seely. After the first battle of Ypres, the First Canadian Division had lost 6000 men. Brigadier General Seely was asked to provide support, but as infantry. He called a full strength parade, presented the proposal and every man volunteered.
The Regiment was in action predominantly as infantry throughout the war. After the second battle of Ypres, the Canadian Cavalry Brigade was sent to France from Belgium on 4 May 1915. Thereafter, the Regiment saw action as infantry and cavalry and was highly commended for its part in the advance on the Hindenburg Line, at Cambrai and through their domination of no-manís-land at Le Verguier. On 30 March 1918 at Moreuil Wood, the Dragoons participated in what was to be the last of the great cavalry charges. Moreuil Wood was a German strong point which the Canadian Cavalry Brigade was ordered to attack:
- A Squadron RCD was to seize the northwest corner of the wood.
- C Squadron was to occupy the southwest face of the wood.
- B Squadron was to gallop around the northwest corner and thrust
at the enemy.
- The LdSH (RC) were to stay behind and develop the attack, and;
- The Fort Gary Horse were to stay in reserve.
Galloping across open ground the RCD met heavy machine gun fire. Turning into the woodline, they engaged in hand-to-hand combat clearing the woods of all enemy. At the end of the 90 minutes battle, 95 Dragoons were either killed, wounded, or missing. The Brigade lost 300 men and more than 800 horses.
After the cease-fire, the Dragoons remained in Belgium until March 1919. At Amiens, a table was dedicated to the Regiment for itís part in the battle. Shortly after, The Regiment, with its new Guidon returned to Canada.