Battle of the Lys (1918)

Strategic developments The German attack zone was in Flanders, from about east of Ypres in Belgium to east of Béthune in France, about south. The front line ran from north-north-east to south-south-west. The Lys River, running from south-west to north-east, crossed the front near Armentières in the middle of this zone. The front was held by the Belgian Army in the far north, by the British Second Army (under Plumer) in the north and centre and by the British First Army (under Horne) in the south. ==Prelude==

Tactical developments The German attacking forces were the Sixth Army in the south (under Ferdinand von Quast), and the Fourth Army in the north (under Friedrich Sixt von Armin). Both armies included substantial numbers of the new stosstruppen, trained to lead attacks with the new stormtroop tactics. The British First Army was a relatively weak force; it included several worn-out formations that had been posted to a "quiet sector". This included two divisions of the Portuguese Expeditionary Corps, which were undermanned, lacked almost half of their officers, had very low morale and were set to be replaced the day of the German attack. German plan of attack The German plan was to break through the First Army, push the Second Army aside to the north, and drive west to the English Channel, cutting off British forces in France from their supply line which ran through the Channel ports of Calais, Dunkirk and Boulogne. ==Battle==

Battle of Estaires (9–11 April) The German bombardment opened on the evening of 7 April, against the southern part of the Allied line between Armentières and Festubert. The barrage continued until dawn on 9 April. The Sixth Army then attacked with eight divisions. The German assault struck the Portuguese 2nd Division, which held a front of about . The Portuguese division was overrun and withdrew towards Estaires after hours of heavy fighting. The British 55th (West Lancashire) Division, to the south of the Portuguese in a more defensible position, pulled back its northern brigade and held its ground for the rest of the battle, despite attacks from two German reserve divisions. The British 40th Division (to the north of the Portuguese) collapsed under the German attack and fell back to the north. Horne committed his reserves (First King Edward's Horse and the 11th Cyclist Battalion) to stem the German breakthrough but they too were defeated. The Germans broke through of front and advanced up to , the most advanced probe reaching Estaires on the Lys. There they were finally halted by British reserve divisions. On 10 April, the Sixth Army tried to push west from Estaires but was contained for a day; pushing north against the flank of the Second Army, it took Armentières. Battle of Messines (10–11 April) troops blinded by poison gas, 10 April 1918 Also on 10 April, German Fourth Army attacked north of Armentières with four divisions, against the British 19th Division. The Second Army had sent its reserves south to the First Army and the Germans broke through, advancing up to on a front, and capturing Messines. The 25th Division to the south, flanked on both sides, withdrew about . By 11 April, the British situation was desperate; it was on this day that Haig issued his famous "backs to the wall" order. Battle of Hazebrouck (12–15 April) On 12 April, the Sixth Army renewed its attack in the south, towards the important supply centre of Hazebrouck, another to the west. The Germans advanced some and captured Merville. On 13 April they were stopped by the First Australian Division, which had been transferred to the area. The British Fourth Division defended Hinges Ridge, the Fifth Division held Nieppe Forest and the 33rd Division was also involved. Battle of Bailleul (13–15 April) From the Germans drove forward in the centre, taking Bailleul, west of Armentières, despite increasing British resistance. Plumer assessed the heavy losses of the Second Army and the defeat of his southern flank and ordered his northern flank to withdraw from Passchendaele to Ypres and the Yser Canal; the Belgian Army to the north conformed. Retirement from Passchendaele Ridge On 23 March, Haig had ordered Plumer to make contingency plans to shorten the line along the Ypres Salient and release troops for the other armies. On 11 April, Plumer authorised a withdrawal of the southern flank of the Second Army and ordered the VIII and II corps in the Passchendaele Salient to retreat the next day into the Battle Zone, behind outposts left in the Forward Zone of the British defensive system. The divisional commanders were ordered that the Forward Zone must be held and that the Germans must not be given the impression that a withdrawal was in progress. At noon on 12 April, the VIII Corps ordered the infantry retirement to begin that night and the 59th Division was withdrawn and transferred south, to be replaced by part of the 41st Division. The II Corps had begun to withdraw its artillery at the same time as VIII Corps on the night of and ordered the 36th and 30th divisions to conform to the VIII Corps withdrawal which were complete by 13 April, without German interference; VIII Corps HQ was transferred to reserve. During 13 April, General Headquarters (GHQ) discussed the retirements in the Lys valley, which had lengthened the British front line and Plumer agreed to a retirement in the Ypres Salient to the Mt Kemmel, Voormezeele ( south of Ypres), White Château ( east of Ypres) to Pilckem Ridge defence line but ordered only that artillery ammunition be carried to the rear; the 4th Army reported on 14 April, that the British were still occupying the Passchendaele Salient. The next day was quiet in the salient and the withdrawal of the II Corps and XXII Corps divisions was covered by the outposts in the original front line and artillery, which was divided into some active batteries which fired and a greater number of batteries kept silent, camouflaged and not to fire except in an emergency. Plumer gave orders to begin the retirement by occupying the line before the night of while maintaining the garrisons in the outpost line and holding the Battle Zone with a few troops as an intermediate line. During the night of the outpost line garrisons were to be withdrawn behind the new front line at and the intermediate line in front of the Battle Zone was to be held as long as possible, to help the troops in the new line to get ready. On 16 April, patrols went forward during the morning and found the area between the old and new front lines to be empty, the Germans still apparently in ignorance of the retirement; one patrol captured a German officer scouting for observation posts who did not know where the British were. Only in the late afternoon did German troops begin to close up to the new line and the British troops in the Battle Zone easily repulsed the German infantry, the 4th Army diary recorded that patrols discovered the withdrawal at that afternoon. Battle of Merckem (17 April) On 17 April, the Belgian Army defeated an attack from Houthulst Forest (The Battle of Merckem) against the 10th and 3rd Belgian divisions from Langemarck to Lake Blankaart by the 58th, 2nd Naval and the 6th Bavarian divisions, with help from the II Corps artillery. The Germans captured Kippe but were forced out by counter-attacks and the line was restored by nightfall. On the afternoon of 27 April, the south end of the outpost line was driven in when Voormezeele was captured, re-captured and then partly captured by the Germans; another outpost line was set up north-east of the village. Belgian losses were 619 killed, wounded or missing. The Germans lost between 1922 and 2354 men, of which 779 were taken prisoner. First Battle of Kemmel (17–19 April) The Kemmelberg is a height commanding the area between Armentières and Ypres. On 17–19 April, the German Fourth Army attacked and was repulsed by the British. Battle of Béthune (18 April) On 18 April, the German Sixth Army attacked south from the breakthrough area toward Béthune but was repulsed. Second Battle of Kemmel (25–26 April) French General Ferdinand Foch had recently assumed supreme command of the Allied forces and on 14 April agreed to send French reserves to the Lys sector. A French division relieved the British defenders of the Kemmelberg. From the German Fourth Army made a sudden attack on the Kemmelberg with three divisions and captured it. This success gained some ground, but there was no progress made toward a new break in the Allied line. Battle of the Scherpenberg (29 April) On 29 April, a final German attack captured the Scherpenberg, a hill to the north-west of the Kemmelberg. ==Aftermath==

Analysis During Georgette, the Germans managed to penetrate Allied lines to a depth of . However, they failed in their main objective to capture Hazebrouck and force a British withdrawal from the Ypres salient. More French reinforcements arrived in the latter part of April, after the Germans had suffered many casualties, especially among the . By 29 April, the German high command realized they could no longer achieve their objectives and called off the offensive. Casualties In 1937, C. B. Davies, J. E. Edmonds and R. G. B. Maxwell-Hyslop, the British official historians gave casualties from as and a similar number of German casualties. Total casualties since 21 March were British: and German: In 1978, Middlebrook wrote of casualties, and Middlebrook estimated French casualties as German as wounded. In 2002, Marix Evans recorded casualties and the loss of British losses of and and French losses of and 12 guns. In 2006 Zabecki gave and casualties. The German flying ace Manfred von Richthofen, the "Red Baron," was killed in action. ==Notes==