Foch began on his right flank, and on 26th September the American army attacked on the Meuse. Next day, the 27th, Haig struck towards Cambrai. The two main defences of the Hindenburg Line were the Canal du Nord, and, behind it, the Scheldt Canal, the latter forming the outwork of the system. The principal German trenches were on the east bank; but on the west bank lay advanced posts, skilfully placed. In one section the canal passed through a tunnel 6,000 yards long, connected by shafts with the trenches above. In another part it lay in a deep cutting, the sides of which were honeycombed with dug-outs. The fortified zone was from 5 to 7 miles wide, and culminated on the east in what was known as the Beaurevoir Line, strongly wired double-trench lines of the same type as those on the western side. On the 27th the Third Army under Byng, and the First Army under Horne, attacked on the left, crossed the Canal du Nord, and by the evening had reached the edge of the Scheldt Canal. Next day that canal had been partially crossed, and Cambrai was menaced from two sides. These events roused acute apprehension in the mind of the German Staff. The crossing of the Canal du Nord by Tanks on the backs of Tanks, and the passing of the Scheldt Canal at its northern end, had shaken their confidence in the outer Hindenburg defences. Next day, the 29th, came Haig’s crowning blow. He struck at the strongest part, and it crumbled before him. The attack was made by Rawlinson’s Fourth Army. For two days his guns had not been silent; the enemy’s garrisons were forced into tunnels and deep dug-outs, and the transport of food and ammunition was made all but impossible. The Germans were, therefore, in a state of confusion and fatigue when Haig attacked at 10 minutes to 6 on the morning of Sunday, the 29th. This action was one of the greatest of the campaign, whether we regard the difficulties to be faced or the strategic value of the gains. Ludendorff was fighting for his last hope, and he had warned his men accordingly. One captured order reminded his troops that "Our present position is our winter position." Another ran: "There can be no question of going back a single step further. We must show the British, French, and Americans that any further attacks on the Hindenburg Line will be utterly broken, and that that Line is an impregnable rampart, with the result that the Entente Powers will condescend to consider the terms of peace which it is absolutely necessary for us to have before we can end the war." Germany was already busy with peace proposals, and she had nothing to bargain with except these defences in the West.