Battle of the Selle
After the Battle of Cambrai, the allies advanced almost 2 miles (3.2 km) and liberated the French towns of Naves and Thun-Saint-Martin. Although the capture of Cambrai was achieved significantly quicker than expected and with moderately low casualties, German resistance north-east of the town stiffened. By 11 October, the Fourth Army had closed up upon the retreating Germans near Le Cateau, with the Germans taking up a new position, immediately to the east of the Selle River. General Henry Rawlinson was faced with three problems: crossing the river, the railway embankment on the far side and the ridge above the embankment. The decision was made to commence the assault at night and as the river was not so very wide at this point, planks would be used for the soldiers to cross in single file. Later, pontoons would be required for the artillery to cross the river. Field Marshal Douglas Haig, aware that the Germans were near exhaustion, initiated a series of operations designed to get British troops in strength across the river and clear a way for a move against the Sambre–Oise Canal, a further 5 miles (8.0 km) to the east.
After a six-day halt for preparations and artillery bombardments Fourth Army troops attacked at 5.20 a.m. on Thursday 17 October. Infantry and tanks, preceded by a creeping barrage, moved forward on a 10 miles (16 km) front south of Le Cateau. The centre and left of the Fourth Army forced crossings of the river, despite unexpectedly strong German resistance and much uncut barbed wire. Fighting was particularly fierce along the line of the Le Cateau–Wassigny railway. The right of the attack, across the upland watershed of the Selle, made most progress and by nightfall the German defences had been broken and Le Cateau captured. Fighting continued from 18–19 October, by which time Fourth Army, much assisted by the French First Army on its right, advanced over 5 miles (8.0 km), harrying the Germans back towards the Sambre–Oise Canal.
The British Third and First Armies, north of the Fourth Army, maintained the offensive pressure the following day. In a surprise joint night attack in the early morning of 20 October, Third Army formations secured the high ground east of the Selle. Following a two-day pause, to bring up heavy artillery, the attack was renewed on 23 October with a major combined assault by Fourth, Third and First Armies; the fighting, which continued into the next day, resulted in further advances. At this stage, the German Army was retreating at a forced but controlled pace. On 24 October, the German Army counterattacked at the Canal de la Dérivation but were repulsed and pushed back by the Belgian Army.