The South African Brigade, like the other troops of assault, were trained for the battle with scientific precision. Models in clay of the German trenches were constructed on the training ground, which was laid out as near as possible to correspond to the enemy front in depth and breadth. Here the attack was practised until each man was made familiar with his proper task. During these days the British artillery was very busy. So great was the concentration of guns that they could have been placed wheel to wheel from end to end of the battle front. Various “Chinese” attacks were organized, as rehearsals and to mislead the enemy. In the third week of March a systematic cutting of the German wire began, and our heavy artillery shelled their back areas and communications. On Thursday, the 5th of April, a steady bombardment opened against all the main German positions, more especially the great fortress of the Vimy Ridge. Wonderful counter-battery work was done, and battery after battery of the enemy was put out of action, located partly by direct observation from the air, and partly by our new device for sound-identification. These were for the most part days of clear, cold, spring weather, with the wind in the north-east; and from dawn to dark our airplanes fought on their own account a mighty battle. The history of that week must rank as an epoch in the campaign in the air. It was a time of heavy losses, for at all costs the foe must be blinded, and the British airmen kept up one continuous offensive. Forty-eight of our own planes failed to return, and forty-six of the enemy’s were destroyed or driven down out of control. The attackers, as was natural, paid the heavier price. The British front of attack was slightly over twelve miles long, from Givenchy-en-Gohelle in the north to a point just short of Croisilles in the south. On the left was the right Corps of Sir Henry Horne’s First Army—the Canadian Corps under Sir Julian Byng, with one British brigade, directed against the Vimy Ridge. On their right lay Sir Edmund Allenby’s Third Army. Its northern Corps, next to the Canadians, was the XVII., under Sir Charles Fergusson, with three divisions in line—from left to right the 51st (Highland Territorial), the 34th, and the 9th; and one, the 4th, in support. The central Corps was Aylmer Haldane’s VI., with, in line, the 15th, 12th, and the 3rd Divisions, and the 37th in support. On the right of the battle was Sir Thomas Snow’s VII. Corps, with the 14th, 56th, and 30th Divisions in line, and the 21st forming a pivot on the right. It is interesting to note that in its constituents the army of assault was largely Scottish. Thirty-eight Scots battalions were destined to go over the parapet—a larger number than the British at Waterloo, and many times the force that Bruce commanded at Bannockburn. [Sidenote: _April 6._]