The Messines ridge, just south of Ypres had been lost to the Germans in the first battle of Ypres, leaving Ypres as a salient[?], sticking out into the German position and overlooked by higher ground on the German side. Field Marshall Sir Douglas Haig, the allied commander, decided to use the salient as a launch point for an offensive into Flanders, designed to break through the front and capture the German submarine bases on the Belgian coast. A successful action would not only put the submarines out of action, but shorten the allied lines and potentially trap a number of German troops behind the new lines.
Engineers from both sides had been tunnelling under the Messines ridge since 1915, until, by the spring of 1917, 21 huge mines had been laid under it with a million tonnes of high explosive. At zero hour at 03:10 on June 7, 1917, after 4 days of artillery bombardment, the allied mines were detonated, and 9 allied infantry divisions attacked, supported by 72 tanks. They managed to achieve the initial objectives due to the huge mines and the fact that the German reserves were too far back to intervene.
Field Marshall Sir Douglas Haig, the allied commander, wanted to continue the battle immediately, but was persuaded to delay further attacks until preparations could be made.
As a second stage of the action, General Sir Hubert Gough[?] was put in charge of the attacks to secure the Gheluvelt Plateau[?] which overlooked Ypres. Huge numbers of guns were moved into the area and started a four-day bombardment, but as always, this simply served to warn the Germans of a coming offensive, allowing them to move in more troops.
On July 4, the Germans used mustard gas for the first time. It attacked sensitive parts of the body, caused sneezing, followed by eyelids swelling, then inflammation of the eyes, blindness for about 10 days and great pain.
One problem in carrying the offensive forward was the Yser canal[?], but this was taken on July 27 when the Allies found the German trenches empty. (Front lines were often vacated at night to reduce the casualties caused by nighttime shelling.)
On July 31, Haig's offensive opened with a major action at Pilckem ridge, with allied gains of up to 2000 yards. The Allies suffered about 32,000 casualties, killed, wounded or missing in this one action.
Ground conditions during the whole Ypres-Passchendaele action were atrocious. Continuous shelling destroyed drainage canals in the area, and unseasonable heavy rain turned the whole area into a sea of mud and filled crater holes. In order to walk up to the front, duckboards[?] were laid across the crater holes. Troops walking up to the front often carried up to 100 pounds of equipment: if they slipped off the path they could slide into a crater and drown before they could be rescued. Bodies buried after previous actions were often uncovered by the rain or later shelling.
During September and October, after awful weather in August and many failures in attack due to poor planning and preparation, a policy of "bite and hold" was adopted by the allies, intending to make small gains which could be held against counterattack. Sir Hubert Plumer[?] had now replaced Gough in command of the offensive.
1,295 guns were concentrated in the area of the attack, approximately 1 gun per 5 yards of attack front. On September 20, at the battle of Menin Road, after a massive bombardment, the Allies attacked and managed to hold their objective of about 1,500 yards gained, despite heavy counter attacks, losing 21,000 casualties. The Germans by this time had a semi-permanent front line, with very deep dugouts and concrete pillboxes, supported by artillery that could be accurately pointed at the attacking troops.
Further advances at Polygon Wood and Broodseinde on the south-western end of the salient accounted for another 2,000 yards and 30,000 casualties. The British line was now overlooked by the Passchendaele ridge and it became an important objective. An advance on October 9 at Poelcapelle was a dismal failure for the Allies, with minor advances by exhausted troops forced back by counter attacks.
The First Battle of Passchendaele, on October 12, 1917 focussed on a further attempt to gain ground around Poelcapelle. Again, the weather was awful, artillery could not be brought closer to the front due to the mud, the Germans were well-prepared and the Allied troops were tired and morale was suffering. The result was 13,000 casualties with minimal gain.
By this point 100,000 men had been lost, for limited gains and no strategic advances.
At this point the Canadian Corp was moved into the line to replace the now decimated Anzac forces. After their successes at Vimy Ridge and Battle of Hill 70[?], the Canadian Corp was considered to be the allies' elite force, and sent into the most horrific of conditions.
Upon his arrival, the CiC General Currie stated that the objective could be achieved, but only with an estimated 16,000 casualties. Haig, by this time innured to such numbers after years of losses in the hundreds of thousands, ordered the offensive to continue, and the Corp moved into the line during mid-October.
On October 26, 1917, the Second Battle of Passchendaele began, the 20,000 men of the 3rd and 4th Canadian divisions advanced up the hills of the salient. A further 12,000 Allied casualties occurred during the day for a gain of a few hundred yards.
Re-enforced with the addition of two British divisions, a second offensive on the October 30 resulted in the capture of the town in blinding rain. For the next five days the force held the town in the face of repeated German shelling and counterattacks, and by the time a second group of re-enforcements arrived on November 6th, 4/5ths of the Canadian Corp had been lost – almost to the man that Currie had predicted.
Their replacements, the Canadian 1st and 2nd divisions. German troops still ringed the area, so a limited attack on the 6th by the remaining troops of the 3rd on a machine gun post allow the 1st to make major advances and gain strong points throughout the area. A follow-up by the 2nd on November 10th completes the battle by pushing the Germans off the slopes to the east of the town. The high-ground was now firmly in allied control.
Haig, remembering the failure to follow through at previous battles, determined to continue the attack, believing that the Germans were ready to break. The attacks achieved at least part of their aims of mutual attrition, reducing the German strength and morale in preparation for attacks elsewhere.
In August and September, 140,000 allies had been killed or wounded, with a further 110,000 in October, and with similar numbers on the German side.
Haig's view was too optimistic though, and the Germans counter-attacked in a major offensive aimed at Paris on March 21, 1918. A subsequent German offensive in the north on April 9-29 (the Battle of the Lys, or the Fourth Battle of Ypres) regained almost all of the ground taken by the allies in the Third Battle of Ypres/Passchendaele.
These battles, and those British and Commonwealth soldiers who gave their lives, are commemorated at the Menin Gate Memorial in Ypres, the Tyne Cot Memorial to the Missing[?], and at the Tyne Cot Cemetery, the largest Commonwealth War Graves Commission cemetery in the world with nearly 12,000 graves.