Battle of Loos The Battle of Loos was the largest British offensive mounted on the Western Front in 1915 during World War I . The first British use of poison gas occurred and the battle was the first mass engagement of New Army units . The British offensive was part of the attempt by the French to break through the German defences in Artois and Champagne and restore a war of movement . Despite improved methods , more ammunition and better equipment the Franco - British attacks were contained by the German armies , except for local losses of ground . Casualties in the ( Autumn Battle ) were high on both sides . Background . Strategic developments . The battle was the British component of the combined Anglo - French offensive known as the Third Battle of Artois . Field Marshal Sir John French and Haig ( GOC British First Army ) , both of whom initially regarded the ground , overlooked by German - held slagheaps and colliery towers , as unsuitable for an attack , persuaded themselves that the Loos attack could succeed , perhaps as the use of gas would allow a decisive victory . Prelude . British offensive preparations . The battle also marked the third use of specialist Royal Engineer tunnelling companies , who deployed mines underground to disrupt enemy defence lines through the use of tunnels and the detonation of large amounts of explosives at zero hour . British plan of attack . Sir John decided to keep a strong reserve consisting of the Cavalry Corps , the Indian Cavalry Corps and Haking ’ s XI Corps , which consisted of the Guards Division and two New Army Divisions ( 21st and 24th ) just arrived in France and a corps staff some of whom had never worked together or served on a staff before . Murray ( Deputy CIGS ) advised French that as troops fresh from training they were suited for the long marches of an exploitation rather than for trench warfare . French was privately doubtful that a breakthrough would be achieved . Haig ( and Foch , Commander of the French Northern Army Group ) wanted the reserves close to hand to exploit a breakthrough on the first day ; French agreed to deploy them closer to the front but still thought they should be committed on the second day . Haig ' s plans were limited by the shortage of artillery ammunition , which meant the preliminary bombardment , essential for success in the emerging trench warfare , was weak . Prior to the British attack , about of chlorine gas was released , with mixed success ; in places the gas was blown back onto British trenches . Due to the inefficiency of the contemporary gas masks , many soldiers removed them as they could not see through the fogged - up talc eyepieces or could barely breathe with them on . This led to some British soldiers being affected by their own gas , as it blew back across their lines . Wanting to be closer to the battle , French had moved to a forward command post at Lilliers , less than behind First Army ’ s front . He left most of his staff behind at GHQ and had no direct telephone link to First Army . Haig ’ s infantry attacked at on 25 September and he sent an officer by car requesting release of the reserves at Battle . The battle opened on 25 September . In many places British artillery had failed to cut the German wire in advance of the attack . Advancing over open fields within range of German machine guns and artillery , British losses were devastating . However , the British were able to break through the weaker German defences and capture the town of Loos , mainly due to numerical superiority . The inevitable supply and communications problems , combined with the late arrival of reserves , meant that the breakthrough could not be exploited . Haig did not hear until that the divisions were moving up to the front . French visited Haig from and agreed that Haig could have the reserve , but rather than using the telephone he drove to Haking ’ s Headquarters and gave the order personally at Haig then heard from Haking at that the reserves were moving forward . When the battle resumed the following day , the Germans were prepared and repulsed attempts to continue the advance . The reserves were committed against strengthened German positions . Rawlinson wrote to the King ' s adviser Stamfordham ( 28 September ) “ From what I can ascertain , some of the divisions did actually reach the enemy ’ s trenches , for their bodies can now be seen on the barbed wire . ” The twelve attacking battalions suffered out of in four hours . Sir John French told Foch on 28 September that a gap could be “ rushed ” just north of Hill 70 , although Foch felt that this would be difficult to coordinate and Haig told him that First Army was in no position for further attacks . The fighting subsided on 28 September , with the British having retreated to their starting positions . Their attacks had cost over including three divisional commanders ; George Thesiger , Thompson Capper and Frederick Wing . Following the initial attacks by the British , the Germans made several attempts to recapture the Hohenzollern Redoubt , which was accomplished on 3 October . On 8 October , the Germans attempted to recapture much of the lost ground , by attacking with five regiments around Loos and part of the 7th Division on the left flank . Foggy weather inhibited onservation , the artiller preparation was inadequate and the British and French defenders were well prepared behind intact wire ; the German attack was repulsed with but managed to disrupt British attack preparations , causing a delay until The British attempted a final attack on 13 October , which failed , due to a lack of hand grenades . General Haig thought it might be possible to launch another attack on 7 November but the combination of heavy rain and accurate German shelling during the second half of October finally persuaded him to abandon the attempt . Major - General Richard Hilton , at that time a Forward Observation Officer , said of the battle : A great deal of nonsense has been written about Loos . The real tragedy of that battle was its nearness to complete success . Most of us who reached the crest of Hill 70 , and survived , were firmly convinced that we had broken through on that Sunday , 25th September 1915 . There seemed to be nothing ahead of us , but an unoccupied and incomplete trench system . The only two things that prevented our advancing into the suburbs of Lens were , firstly , the exhaustion of the " Jocks " themselves ( for they had undergone a bellyfull of marching and fighting that day ) and , secondly , the flanking fire of numerous German machine - guns , which swept that bare hill from some factory buildings in Cite St . Auguste to the south of us . All that we needed was more artillery ammunition to blast those clearly - located machine - guns , plus some fresh infantry to take over from the weary and depleted " Jocks . " But , alas , neither ammunition nor reinforcements were immediately available , and the great opportunity passed . Air operations . The Royal Flying Corps ( RFC ) came under the command of Brigadier - General Hugh Trenchard . The wings under colonels E . B . Ashmore , John Salmond and Sefton Brancker respectively , participated . As the British had a limited amount of artillery ammunition , the RFC flew target identification sorties prior to the battle to ensure that shells were not wasted . During the first few days of the attack , target - marking squadrons with better wireless transmitters , helped to direct British artillery onto German targets . Later in the battle pilots carried out a tactical bombing operation for the first time in history . Aircraft of the wings dropped many bombs on German troops , trains , rail lines and marshalling yards . As the land offensive stalled , British pilots and observers flew low over enemy positions , providing targeting information to the artillery . Aftermath . Analysis . French had already been criticised before the battle and lost his remaining support in both the Government and Army as a result of the British failure at Loos and his perceived poor handling of his reserve divisions in the battle . He was replaced by Haig as Commander of the British Expeditionary Force in December 1915 . Casualties . British casualties in the main attack were the subsidiary attack , a total of of the on the Western Front in 1915 . Edmonds the British Official Historian gave German losses in the period as of casualties on the Western Front , during the autumn offensives in Artois and Champagne . In losses of the Sixth Army are given as 21 September ; by the end of October losses had risen to and total German casualties for the autumn battles ( ) in Artois and Champagne were given as Commemoration . The Loos Memorial commemorates over who fell in the battle and have no known grave . The community of Loos , British Columbia ' s name was changed to commemorate the battle . Several survivors wrote of their experiences , the poet Robert Graves described the battle and succeeding days in his war memoir " Goodbye to All That " . Author Patrick MacGill , who served as a stretcher - bearer in the London Irish and was wounded at Loos in October 1915 , described the battle in his autobiographical novel " The Great Push " . J . N . Hall related his experiences in the British Army at Loos in " Kitchener ' s Mob " .