The PPCLI served for a year with the 80th Brigade before joining the new 7th Brigade within the 3rd Canadian Division on December 22, 1915. In 1916 the regiment fought major battles at Mount Sorrel and on the Somme. It was not until October 1916 that the first Canadian, Lt Col Agar Adamson, was appointed to command the regiment. In 1917 as part of the Canadian Corps, the regiment took part in the Battle of Vimy Ridge on April 9, 1917, and Passchendaele later the same year. In 1918 the regiment fought at the Battle of Amiens, Jigsaw Wood, and the Battle of the Canal du Nord as part of the great battles of the Hundred Days that ended the war. The 4th Company, PPCLI, entered Mons with other Canadian troops early on November 11, 1918, before the armistice took effect at 11 AM.