Blackburn went on leave in France from 29 April to 7 May. The 10th Battalion entered the fighting on the Western Front in June, initially in the quiet Armentières sector of the front line. While in this area, Blackburn was selected as a member of a special raiding party led by Captain Bill McCann. In the early hours of 23 July, the 10th Battalion was committed to its first significant action on the Western Front during the Battle of Pozières, part of the Battle of the Somme. Initially, A Company under McCann were sent forward to assist the 9th Battalion, which was involved in a bomb (hand grenade) fight over the O.G.1 trench system. Held up by heavy machine gun fire and bombs, McCann, who had been wounded in the head, reported to the commanding officer (CO) of the 9th Battalion, Lieutenant Colonel James Robertson, that more help was needed. About 05:30, a detachment of 50 men based on 16 Platoon, D Company, 10th Battalion, was then sent forward under Blackburn to drive the Germans out of a section of trench. Blackburn, finding that A Company had suffered heavy casualties, immediately led his men in rushing a barricade across the trench. Breaking it down, and using bombs, they pushed the Germans back. Beyond this point, preceding artillery bombardments had almost obliterated the trench, and forward movement was exposed to heavy machine gun fire.