 Foreign intelligence gathering by the Germans, big Allied trench raids and troop concentrations seen west of Arras, made it clear to the Germans that a spring offensive in the area was being prepared.In February 1917, a German-born Canadian soldier deserted and helped confirm many of the suspicions held by the Germans, providing them with a great deal of useful information.By March 1917, the 6th Army knew that an offensive was imminent and would include operations aimed at capturing Vimy Ridge.