When World War I broke out, the Dragoons volunteered as a unit. In December of that year, Griesbach was promoted to major assigned to command the 49th Battalion. He was able to recruit 1000 men in eight days in January 1915. The unit served in various engagements, including the Battle of Vimy Ridge, the Battle of Arras, the Third Battle of Ypres, and the liberation of Mons. In 1917, Griesbach was promoted to Brigadier-General and assigned command of the 1st Canadian Infantry Brigade of the 1st Canadian Division.