The Germans next attacked the Princess Patricias in the communication trenches, bombing their way along to the apex line then lightly held. Colonel Buller was killed while rallying the support platoons in the communication trench. A close and dreadful struggle ensued between Germans and Canadians in the communication trenches. The latter endeavored to build blocks down the communication trenches to hold the enemy from reaching the support line until it had been fully manned. The garrison of each block perished while a new one farther on was being built. They kept off the enemy long enough, however, for the reserve company to come up and the vital position was saved. Had the support line gone, the Ypres salient would have gone with it. Colonel Buller saved the day by holding on until General Macdonell could bring up his reserve. Captain Niven meanwhile was clinging to the knoll of trenches in the front line to the northwest, threatened on all sides by the Germans. His right-hand platoon had been smashed by the bombardment and Lieutenant Haggerty was killed. Lieutenant Molson took over the command, but, being wounded, the section had to be abandoned. Lieutenants Triggs and Irwin, the latter the only remaining subaltern, were wounded later in the day. Captain Niven, though wounded, and the only officer remaining of his company, continued to command. All communication with the battalion was cut off, but some runners got through. At twilight Captain Niven gave up his command to Lieutenant Glascoe from headquarters, and after having his wound dressed returned to his company, only to be struck down by a bullet. Lieutenant Glascoe, seeing the surviving party would soon be surrounded, brought away the remnant to the support line in safety. Lieutenant C. P. Cotton of the First Divisional Artillery in command of the gun crews serving two 18-pounders continued to fire upon the enemy coming over Observatory Ridge until they were within a few yards of the gun pits. Lieutenant Cotton and the gun crews fought to the last.