W. A. Willison, Canadian correspondent, cabled from the Picardy front on March 22, 1918:

While British and German troops were struggling far to the south in the opening clash of the Spring campaign, the greatest projector gas bombardment in the world's history was carried out by the Canadians tonight against the enemy positions between Lens and Hill 70. Sharply at 11 o'clock the signal rocket gave notice of the beginning. A moment later over 5,000 drums of lethal gas were simultaneously released from projectors, and were hurled into the enemy territory from the outskirts of Lens, and northward to CitÉ St. Auguste and the Bois de Dix-Huit.

From his front lines and strong points favoring winds carried the poisonous clouds back upon the enemy's supports, reserves, and assembly areas. The whole of the front was lit up with enemy flares, dimly seen through the heavy mist, while the men in our lines could hear the enemy's gas alarms and cries of distress from the hostile trenches.

Nine minutes later our field artillery, supported by heavy guns and heavy trench mortars, opened up with a slow bombardment, which gradually increased in intensity, until, forty minutes later, the enemy positions were swept with a short, intensive, creeping barrage, which raked his forward and rear areas with high explosive. Caught by our gas without a moment's warning, caught again as he was emerging from his shelters by our artillery, the enemy's casualties must have been very heavy, for the effectiveness of our smaller gas operations has been emphatically proved by the evidence of prisoners.

Tonight's bombardment was three times greater than anything of its kind ever attempted by us on the Western front, and much greater than anything ever launched by the Germans, though the score of the second battle of Ypres and other reckonings are still to be settled, and will be settled.