The Gheluvelt Plateau became a sea of mud, flooded shell craters, fallen trees and barbed wire. Troops were exhausted quickly by the weather, massed artillery bombardments and lack of food and water; rapid relief of units spread the exhaustion through all the infantry, despite the front being held by fresh divisions. British artillery fired a preparatory bombardment from Polygon Wood to Langemarck but the German guns concentrated on the Plateau. The British gunners were hampered by low cloud and rain, which made air observation extremely difficult and shells were wasted on empty gun emplacements. The British 25th Division, 18th (Eastern) Division and the German 54th Division had relieved the original divisions by 4 August but the German 52nd Reserve Division was left in the line; the infantry of both sides were exhausted by 10 August. The 18th (Eastern) Division attacked on the right; some troops quickly reached their objectives but German artillery isolated them around Inverness Copse and Glencorse Wood. German troops counter-attacked several times and by nightfall the Copse and all but the north-west corner of Glencorse Wood had been recaptured. The 25th Division on the left flank advanced quickly and reached its objectives by rushing the Germans in Westhoek. Snipers and attacks by German aircraft caused an increasing number of casualties; the Germans counter-attacked into the night and the British guns bombarded German troops in their assembly positions. The appalling weather and costly defeats began a slump in British infantry morale; lack of replacements began to concern the German commanders.