The Flanders plain spread almost flat from the French border into Belgium, broken only by a line of low hills from Cassel east to Mont Kemmel. From Kemmel, a ridge ran northeast past Ypres, through Wytschaete and Gheluvelt to Passchendaele. In autumn, the water table rose to the surface, filling any depression until the sides collapsed. Roads closed during thaws to preserve their surfaces. The rest of the plain was woods and small fields divided by hedgerows planted with trees. The terrain made infantry observation nearly impossible, mounted action futile due to countless obstructions, and artillery difficult with limited fields of view. South of La Bassee Canal lay coal mines with slag heaps and pit-heads. North of the canal, Lille, Tourcoing, and Roubaix formed an industrial complex. Both armies would learn to hate this ground.

The 1st and 2nd Cavalry divisions under General Allenby covered the assembly of III Corps at St. Omer and Hazebrouck, ordered to extend as far north as Ypres. On October 12, British cavalry found Germans dug in on Mont des Cats. The 3rd Cavalry Brigade attacked uphill through hop-fields toward the monastery, dismounted cavalry from the west and mounted cavalry with horse artillery from the south. The cavalry pushed forward over successive days, occupying Mont Noir, Dranoutre, and Kemmel. By October 15, they held the Lys River from Armentieres to Comines and the Comines canal to Ypres. But fog grounded reconnaissance aircraft, the Lys was a muddy stream flanked by water meadows, and the cavalry on roads could not dislodge well-defended German crossings.

The German 26th Wurttemberg Division began its offensive and broke into Messines after nearly five hours of fighting, infantry from Brigade 51 facing vastly outnumbered British cavalry. The British fought house-to-house before retreating out of the town. The 9th and 13th brigades of II Corps arrived and advanced toward the Messines road, engaging the 6th Bavarian Division. Wytschaete, held by just 200 men of the Household Cavalry Composite Regiment, fell under attack from six German battalions. The 12th Lancers recaptured the town, but the Lincolns and Northumberland Fusiliers lost half their strength trying to retake the ridge. By November 1, the Germans had secured both Messines and Wytschaete, though the French 32nd Division held ridges to the west.

The British 7th Division was withdrawn from the line, reduced to a shadow of its original strength, and replaced by the 8th Division from Britain. The Germans had also suffered high losses and needed to pause to reinforce their formations. The front fell quiet, limited to raids and the heavy shelling of Ypres by German artillery. The Germans made their last effort against Ypres on November 10. The Race to the Sea was over. From the Swiss border to the Belgian coast, a continuous line of trenches would soon stretch, and the war of movement that generals had anticipated became the static nightmare of the Western Front.

The French had used undamaged railways behind their front to move troops faster than the Germans, who faced long detours and damaged tracks. The French IV Corps moved from Lorraine and assembled in four days, troops traveling up to 100 kilometers per day using hundreds of motor vehicles coordinated by staff officers. French use of Belgian and captured German rail wagons, plus domestic telephone and telegraph systems, gave them intelligence advantages. Information on German troop movements from wireless interception enabled the French to forestall German moves, while the Germans relied on frequently wrong spy reports. The initiative Germany held in August was never recovered. In Flanders, the first winter of the Great War settled over the battlefields, and the Messines Ridge would wait three more years for the mines that would finally shake it loose.