In preparation for the Battle of Vimy Ridge on April 9, two problems  that had to be solved were how to safely get the troops close enough to German lines, and how to safely get them across No Man’s Land to attack.

Twelve tunnel systems were dug, allowing attacking troops to amass safely underground prior to the attack and emerge close to the front lines.

Beginning March 20, a 20-day bombardment began, moving up and down the front to hide from the Germans where the main attack would happen. The Germans called this week the “week of suffering” as more than one million rounds were fired, obliterating trenches and defensive wire in No Man’s Land and starving the German lines of supplies.

Parts 1 and 2 of the excellent 10-part National Film Board of Canada series on the Battle of Vimy Ridge, describe the preparations.