The British attack began at on 31 July; the attack was to commence at dawn but a layer of unbroken low cloud meant that it was still dark when the infantry advanced. The main attack, by II Corps across the Ghelveult Plateau to the south, confronted the principal German defensive concentration of artillery, ground-holding divisions () and divisions. The attack had most success on the northern flank, on the fronts of XIV Corps and the French First Army, both of which advanced to the line of the Steenbeek river. In the centre, XVIII Corps and XIX Corps pushed forward to the line of the Steenbeek (black line) to consolidate and sent fresh troops towards the green line and on the XIX Corps front to the red line, for an advance of about . Group Ypres counter-attacked the flanks of the British break-in, supported by every artillery piece and aircraft within range, around noon. The Germans were able to drive the three British brigades back to the black line with casualties; the German advance was stopped at the black line by mud, artillery and machine-gun fire.