The Lys in the First World War

The Lys, in Dutch the Leie, is a river that rises in northern France, flows through French Flanders and along the Belgian border, and joins the Scheldt at Ghent. In the autumn of 1914 a front settled in its valley, between Armentières and the area around Neuve-Chapelle, and for three and a half years it barely moved. In April 1918 the river gave its name to the second great German offensive of that spring. In October the Allies crossed it at Kortrijk and pushed on, deeper into Belgium.

Cavalry and trenches (1914)

In early October 1914 German cavalry corps roamed the plain along the Lys, trying, during the race to the sea, to get round the Allied left flank. On 11 October Bavarian cavalrymen crossed the bridge over the Lys at Estaires driving civilians ahead of them as a human shield, while further downstream, at Wervik and Menin, uhlans crossed the river, which there forms the Belgian–French border.

On 13 October the British III Corps of General William Pulteney went over to the attack. In the Battle of Armentières it seized the bridges over the Lys at Sailly, Bac-Saint-Maur and Erquinghem, and on 17 October it entered Armentières, a textile town on the river that the Germans had left in a hurry. It did not reach Lille, but it held the Germans on the line of the Lys. On this sector, between Armentières and Ploegsteert Wood, British and Saxon soldiers made one of the best-known Christmas truces in December 1914.

A quiet sector (1915–1917)

The ground along the Lys was flat and marshy. Instead of trenches, breastworks of sandbags were built here, and a major attack was usually possible only from May. In March 1915 the British fought the Battle of Neuve Chapelle in this valley, but afterwards the sector was considered quiet. From 1917 it was held by the Portuguese Expeditionary Corps, whose trenches the Germans first attacked in June that year. In June 1917, after the Battle of Messines, the Germans fell back towards new defences along the canal and the Lys, and their batteries south of the river inflicted most of the British losses in that battle.

The offensive on the Lys (April 1918)

The spring of 1918 was exceptionally dry. On 9 April at 4.15 a.m. the German Sixth Army opened its bombardment and struck the Portuguese. So began the Battle of the Lys, the operation codenamed “Georgette”. Within a few hours the Portuguese 2nd Division ceased to exist as an organised force, and the Germans reached the Lawe and the Lys and crossed the Lys at Bac-Saint-Maur. In the Battle of Estaires they also crossed the river at Estaires, and on 11 April they took Armentières and Merville. They had earlier drenched Armentières with mustard gas shells and took it without an assault, once the British had withdrawn through the ruins to the north bank of the river. That day Douglas Haig issued his order to fight “with our backs to the wall”.

From the breach on the Lys the Germans drove on the railway junction at Hazebrouck, but in the Battle of Hazebrouck they were stopped in front of the Forest of Nieppe. They still took Mount Kemmel, and on 29 April they called off the attack. Each side lost some 100,000–120,000 men. Instead of a breakthrough the Germans had a projecting, flat salient in the river valley, shelled by the Allies from the surrounding hills.

Across the river to the east (August–October 1918)

In the summer the Germans began to leave this salient. On 19 August the British re-entered Merville, and on 3 October the ruins of Armentières. To the north, in the Fifth Battle of Ypres, the Belgians, British and French retook the hills around Ypres and reached the Lys.

On 14 October the Flanders Army Group of King Albert I opened the Battle of Kortrijk on a front from the Lys at Comines to Diksmuide. On 15 October the British entered Menen, where the Germans had blown all the bridges, and crossed the river at Comines. On 19 October they crossed it in boats at Kortrijk, and by the morning of 20 October the whole front of the British Second Army was across the Lys. From 20 October the Army Group pressed on towards the Lys and the Scheldt and on to Ghent, which the Belgians entered on 10 November.