The Battle of the Lys (, ) was a major battle between Belgian and German forces during the German invasion of Belgium of 1940 and the final major battle fought by Belgian troops before their surrender on 28 May. The battle was the bloodiest of the 18 Days' Campaign. The battle was named after the Leie (French: Lys), the river at which the battlefield occurred.
Battle
Initial fighting
On 24 May, a heavy German attack forced Allied troops to fall back at Kortrijk over the Lys to the 1st and 3rd Belgian divisions. The Belgians had been persuaded to abandon the Scheldt and withdraw to relieve British troops for an Allied counter-offensive, but that strategically did little to alleviate the situation at the front. With the Allied line facing four German divisions, the 9th and 10th Belgian Divisions rushed in to reinforce the position. The Belgian II Army Corps launched a counter-attack and captured 200 German soldiers. Belgian artillery opened up effectively on the Germans, but Allied lines were subject to numerous bombing raids and strafing runs, with negligible air support of their own. A German division from Menen moved up to Ypres, threatening to cut the Belgian Army off from the British. The Belgians' 2nd Cavalry Brigade and 6th Infantry Division came in to support the area and managed to hold off the Germans.
On 25 May, the British, realizing that further counteroffensives were no longer possible, began to withdraw to the port of Dunkirk. All hopes of saving the Belgian Army were lost. It became clear from this point on that all the Belgians could do was buy enough time for the Allies to evacuate. The British spared a brigade and a machine gun battalion, their only reserves, to assist in the delay. At 06:30, the 12th Royal Lancers, an armoured car regiment, was dispatched to the north of the Lys to cover the left flank of the British 2nd Army Corps and reestablish contact with the Belgians in the area. The regiment reported that the Belgians were retreating in the face of superior forces, and they themselves sporadically engaged the Germans. In an order to his troops that day, King Leopold III informed the Army, "Whatever may happen, I shall share your fate". Low morale prompted sections of the Belgian 5th and 17th regiments to surrender the bridgehead at Meigem without a fight. That was in direct contradiction of their officer's orders, which were ignored. In one instance, fed-up soldiers shot their superiors. The elite Chasseurs Ardennais were deployed to the small village of Vinkt. Here the 1st Division successfully repulsed numerous attacks by Germany's 56th Infantry Division. Lieutenant Colonel George Davy, head of the British Military Mission to the Belgian Army Headquarters, was informed that the Belgians would be unable to extend their front any further. Starting that night, 2,000 wagons were lined up side by side along the rail line from Roeselare to Ypres to act as an improvised anti-tank barrier.
Belgian position worsens
By 26 May the Allied position was becoming desperate. The Belgians were struggling to hold Izegem, Nevele, and Ronsele. The Chasseurs Ardennais held their ground against the 56th division, which was subsequently replaced by the 225th Infantry Division. The German 256th Infantry Division managed to cross over the canal at Balgerhoeck and attack Eeklo. The Belgian Lanciers Regiment abandoned Passchendaele and Zonnebeke, and British engineers blew up the Menin Gate bridge. Fresh German units threatened to split the Belgian and British lines, but their attack was blunted by a Belgian infantry division and a cavalry division. An additional infantry division maintained the integrity of the defensive line. All of Belgium's reserves were deployed, and auxiliary troops began arming themselves with 75mm guns from training centers to form the rear. The Belgian Command began resorting to flooding the canals to contain the Germans. At midday the Belgian Army informed the French head of the mission to the Army Headquarters, General Pierre Champon that "the Army has nearly reached the limits of its endurance". At 18:00, French General Georges Blanchard arrived to inform Leopold that the British were withdrawing further to the rear on the Lille-Ypres line. Lord Gort ordered Major General Harold Franklyn to man the dry Comines-Ypres Canal with the 5th Infantry Division to cover the withdrawal towards Dunkirk. That evening, Leopold began making plans to relocate his headquarters to Middelkerke.