Birks' battalion were ordered to attack and capture the German line parallel to them, and the men moved towards their positions from Zillebeke on the night of 18 September, coming under some fire from gas shells. 19 September was incident-free, with the battalion preparing to attack the next day, in what would become known as the Battle of Menin Road. Early in the morning of the 20th, a "light drizzle" fell over the battlefield and at 4am the Germans sent barrages in front of and behind the battalion's position. At 5:40am, the battalion advanced.
The first resistance was met by Birks and a corporal, taking two machine-gun positions as another group of officers rushed a strong post. They were attacked with bombs, and the corporal was seriously wounded. Birks continued on alone. Reaching the rear of the pillbox, he forced the occupants to surrender. Birks then led an attack a series of dugouts and pillboxes on the edge of Glencorse Wood, and fought against machine gun and bombs. He also assisted in the reorganisation and consolidation of Australian men who had drifted away from their unit.
The next day, 21 September, enemy shelling in response to the movement of Allied artillery had buried some men in Birks' platoon. Birks attempted to dig out these men, "standing exposed", but another shell aimed at the C Coy post killed Birks, and four others, before he could save them.