Easter Monday 1917 brought a howling wind with sleet and snow to the German lines. The defenders were going through a terrible period under the constant pounding of the Allied artillery bombardment.
Suddenly at 05:30 hours there was a change, the barrage had moved slightly, then it moved again.
A sap is a shallow tunnel which can be swiftly opened up allowing previously hidden troops to proceed directly to the assault. The Canadians had made good use of saps and in places were able to deliver troops right up to their own front lines.
The change in the bombardment had been brought about by the artillery moving their sights to just in front of their infantry.
As my Canadian guide at Vimy aptly described it, the Germans were faced with this curtain of falling steel. They could neither see through it nor respond. By the time it had moved behind their positions, the Canadians were upon them.
By midday the 1st and 2nd Divisions had swept across the flat ground towards the villages of Thélus and Farbus. Their greatest obstacle had been the German second line which was well placed and heavily defended with machine gun posts.
The 2nd Division had the British 13th Brigade under its command, and it was they that pushed through to the outskirts of Vimy and the 2nd Division's final objective for the day.
Amongst the 13th Brigade were the 2nd Bn KOSB. At the battle of Loos 18 months earlier the 7th Bn KOSB had served with distinction at the battle of Loos whilst backing up the failed French attempt on Vimy.
Hill 145, in front of the 4th Division is the highest point on the ridge and commands the Douai Plain behind it. It was the keystone to the German's position and had been fortified to withstand all assaults.
The Canadians found themselves coming under enfilading fire from a position just to the west called The Pimple a hill immediately in front of the village of Souchez.
A decision was taken that Hill 145 was of greater significance than The Pimple and troops were diverted to try and secure the last part of Vimy Ridge still in German hands.
On the afternoon of 10 April, Hill 145 finally fell and the Canadian Corps were masters of the ridge. Having lost their positions the Germans were forced to pull back a sufficient distance away from the ridge and this led to the fall of The Pimple on 12 April.
Having stormed the heights of Vimy Ridge in such a stunning fashion the Canadians could well have been disappointed to discover that the British offensive to the east of Arras had not met with a great deal of success, and that the mud had severely hindered their artillery's efforts to get the guns forward to support a second push.
This was a problem that dogged the generals of both sides throughout the period of trench warfare. To gain the enemy's positions you needed to bombard it and the rear areas into oblivion. The infantry, however, couldn't advance any further than that curtain of steel would let them.
The guns had to be moved forward over the area that had just been churned into a mire. They then had to be fired without sinking themselves in that mud. In this case it couldn't be done.
Canadians had been trained to use German field guns, and did, but the moment had been lost.
The costs to the Canadians were about 3,500 killed and a further 7,000 men injured. The first wave battalions suffering particularly heavy casualties.
After the war, Canada's greatest monument to her met-at-arms was raised on the site of Hill 145. It was only fitting, for here on the muddy slopes of an Artois hill a nation was truly born: Canada.