36th (Ulster) Division crosses the River Lys.

Saturday, 19 October, 1918
Detail from the Queen's Colour of The Royal Irish Fusilers

Great gains were being made all along the Western Front in the first weeks of October 1918. The 36th (Ulster) Division was to advance to the River Lys and drive the enemy out of the industrial area of Lille-Tourcoing-Roubaix. The attack began on 14 October and by 16 October it reached the line of the Lys where the Germans had blown the bridges. Despite D Company of the 9th Battalion The Royal Irish Fusiliers* getting a group across a pontoon bridge, it was cut off when effective German artillery fire damaged the bridge. They did manage to return in a boat with six prisoners and two captured machine guns.

A new plan to cross the Lys was made and the Ulster Division was to cross north-east of Courtrai. The 9th Inniskillings crossed the Lys on the night of 19 October and when joined by the 1st Inniskillings, established a bridgehead. The 15th Royal Irish rifles, as part of 107 brigade, began to cross at 0200 hours the following day. The Ulster Division was the first allied formation to cross the river and the advances were only halted on 22 October to allow the French to secure the Division's flank. When the artillery crossed the Lys the advance continued and on 22/23 October, the Germans withdrew about one mile along several miles of the front. The Division doggedly continued the advance, pursuing the Germans through gas shells, and murderous artillery and machine-gun fire until relief began on 27 October. The Commander II Corps congratulated the Division stating:

When the history is written of what the Division has done in Flanders during the past month, it will prove to be a record of magnificent fighting and wonderful progress; for during this period; an advance has been made of about twenty-five miles over the worst of country, and under the heaviest machine-gun fire ever experienced in this War. The advance has entailed constant fighting, but the 36th Division had overcome every obstacle, and has proved itself one of the best fighting Divisions in the Army, well commanded and well staffed.

The Battle Honour LYS was not carried forward when The Royal Irish Rangers was formed from its antecedent regiments in 1968.