General Sir Douglas Haig, the Commander-in-Chief (C-in-C) of the BEF, had decided that the main British Advance for 1917 would take place in the Ypres Salient. He intended to drive east from Ypres towards Passchendaele and on to the coast in an effort to deny the use of the Belgium North Sea ports to the German Navy, thereby relieving the British South Coast ports from harassment by the enemy and securing his vital supply routes from Britain.
To the south and east of Ypres a belt of high ground runs southwest from the Gheluvelt plateau through Mount Sorrell, Hill 60 and St Eloi; before turning southwards to run through the village of Wytschaete (Wijtschaete) and on to Messines before dropping down towards Ploegstreet Wood. The Germans had captured this high ground during the First Battle of Ypres and from here they could dominate the surrounding countryside. It gave them a distinct advantage over the British, as they could see north across the Ypres Salient and observe most of what went on in the area. It was vital, therefore, that the Germans were ejected from this ridge if General Haig's planned offensive was to take place.
The task of removing the Germans from this high ground, which the British called the Messines Ridge, was given to General Sir Herbert Charles Onslow Plumer's British Second Army.
General Plumer was a meticulous planner and had gained a reputation for caring about his men, which had earned him the nickname 'Daddy Plumer'. He had learned the lessons of the 1916 Battles of the Somme and the need to concentrate his artillery. For the assault against the Messines Ridge he had over 2,000 guns, a third of which were heavy or medium batteries, at his disposal and thus allocated a medium or heavy gun to every 40 metres of front. 144,000 tons of shells were allotted to the attack and in the seven-day preliminary bombardment 3.5 million artillery rounds of all sizes would be fired.
By this stage of the war, the Germans had adopted a new tactic for their defence and were employing fortified strong points to garrison their frontline with counter-attack Battalions ready to reinforce any area that was threatened. The British as a consequence had developed tactics to deal with these strong points that entailed getting up close to the fortified strongpoints before assaulting them at close range with grenades and bombs.
As part of his preparations for the battle General Plumer had a huge scale model of the terrain of the Messines Ridge built at Scherpenberg behind the British frontline. In the weeks and days leading up to the battle groups of all ranks from the units that would take part spent hours going over this model getting familiar with the ground over which they were to fight. Time was also devoted to going over their plans in order to ensure that each man had a clear understanding what was expected of them.
The Opposing Forces
The situation that existed on the Western Front in 1917 was such that neither side could do much without the other knowing something was going on and that the best one could hope to achieve was to keep them guessing exactly what it was that you were doing. The Germans knew as far back as January 1917 that something was up in the Messines Ridge area. They had detected the movement of British Artillery Batteries into the Messines area in February 1917, but when the Battle of Arras broke out further south in April 1917 they considered that to be the main British assault.
They had significantly reinforced the Messines Ridge area with the II Bavarian Corps of the German Sixth Army being detached and put under command of General Friedrich Bertram Sixt von Armin's German Fourth Army to ensure cohesion of their defences. In addition the 24th Division and 40th (Saxon) Division were moved to the south of Ypres to reinforce the Wytschaete Group made up of Divisions from the German XIX Corps. The XIX Corps was to the north of the River Douve and the II Bavarian's were to the south.
By the time that the British launched their 7th June assault there were seven German Divisions active in the area. In the north opposite Hill 60 and Caterpillar was the 204th Division, further south opposite St Eloi was the 35th Division, in the area of Wytschaete was the 2nd Division. The severely depleted 3rd Bavarian Division, which had already lost some 2,000 men at Arras, was brought up as a counter- attack Division and the 4th Bavarian Division closed up to the south of the River Douvre to strengthen that area. The 24th Division was inserted into the German line to the north of Wytschaete and the 40th Division was in the process of relieving the 3rd Bavarians.
The British would commit General Plumer's Second Army to the assault and this consisted of three Corps. In the north opposite the 204th and 35th German Divisions was the British IX Corps, in the centre opposite the 24th and 2nd Divisions was the British X Corps and in the south opposite the 3rd Bavarian and 4th Bavarian Divisions was the II ANZAC Corps.
Thus the British had a 2:1 advantage in the Messines area over their German adversaries on 7th June 1917.
The British Plan
The British plan was to simultaneously detonate 25 mines along 9 miles of the German frontline on the Messines Ridge and then assault in their immediate wake with three Divisions up in each Corps area closely supported by artillery.
The Artillery Fire Plan included the now almost obligatory preliminary bombardment which took place over the preceding seven-days. The preliminary bombardment would cease at 02:50am to allow the German defenders to re-occupy their positions before the mines were set off at 03:10 hrs. The artillery would resume firing at the same moment as the explosion of the mines. Most of the 18-pounder field guns were to fire a creeping barrage of shrapnel immediately ahead of the advancing infantrymen, while the other field guns and 4.5 inch howitzers fired a standing barrage some 700 yards (640 metres) further ahead. The standing barrage would initially fall on the German forward positions and then lift to the next target when the advance got within 400 yards (370 metres) of it. As each objective was taken by the infantry, the creeping barrage would pause 150 to 300 yards (140 to 270 metres) ahead and become a standing barrage, in order to provide protective fire whilst the newly gained positions were consolidated. During this period the rate of fire slackened to one round per minute per gun, allowing the gun-crews a respite, before resuming full intensity as the barrage moved on. The heavy artillery fired on the German rear areas and over 700 machine guns participated in the barrage firing over the heads of the advancing troops.
The British IX Corps would assault with the British 23rd Division in the area of Hill 60 and Caterpillar, the British 47th (2nd London) Division in the area between Caterpillar and St Eloi and the 41st Division at St Eloi. The 24th Division would be in reserve. The British X Corps would assault with the British 19th (Western) Division to the north of Wytschaete, the British 16th (Irish) Division at Wytschaete and the 36th (Ulster) Division between Wytschaete and Messines. The 11th (Northern) Division would be in reserve. The II ANZAC Corps would assault with the British 25th Division to the north of Messines, the New Zealand Division to the south of Messines and the 3rd Australian Division to the south of the River Douve. The 4th Australian Divisions would be in reserve.
The new Mark IV tanks that had recently arrived in France were also to be used in the assault. 16 were attached to the British IX Corps, 12 to the British X Corps, 20 to the II ANZAC Corps and 24 were kept in reserve for the afternoon push.
The new Mk IVs were not greatly different to those used in September 1916, they could travel a little further, was more comfortable and was now equipped with Lewis Guns rather than Vickers or Hotchkiss. The armour had been upgraded to withstand current German armour piercing rounds. It still had a crew of an officer and seven men and could travel at the remarkable speed of 2mph. The Males were equipped with two 6-pounder (57mm) guns and 4 Lewis Guns, whilst Females were equipped with 6 Lewis Guns. To cover the noise of their approach, the Royal Flying Corps was tasked with flying sorties low over the German frontlines at 02:00am on the morning of the assault.
Zero hour was set for 03:10 hrs on the morning of 7th June 1917 when there would be just enough light for the assaulting troops to see where they were going whilst the Germans in their frontlines and on the ridge would still be unable to have a clear view of what was happening.
Both sides had mining operations underway in the Ypres Salient area, but the Germans, whilst carrying out counter-mining, were seemingly unaware of the scale of the British mining preparations for the battle. They believed that their own counter-mining activities were successful and thus sufficient to ensure that no major mining threat existed in the Messines Ridge area at this time. In addition the German defences were now far more elastic in nature and the frontlines less heavily manned than had previously been the case. They now tended to rely on concrete strong points with Battalions held back in reserve to mount immediate counter-attacks in the event of a British offensive. They believed therefore that the potential use of mines could not have a significant impact on their defensive entrenchments.
In preparation for the Battle of Messines, the British dug 25 mines which stretched out beneath no-man's-land and underneath the German frontline strong points. Each of these mines was loaded with Ammonal ready to be detonated at the start of their attack.
19 of these mines were set off on 7th June 1917 and six were not. The six that were not detonated were: -
It was the 1st Australian Tunnelling Company who constructed the two most northern mines at Hill 60 and Caterpillar which were detonated at the opening of the Battle of Messines on 7th June 1917. The story behind the digging of these mines was used as the basis of the film 'Beneath Hill 60' which was released in 2010.
One of the Australians who worked on the mines, Sapper Roll, described what happened when the mines went off: "The whole hillside rocked like a ship at sea. The noise of the artillery was deafening and the thunder of our charges was enormous. The infantry dashed forward under a barrage and kept sending back thousands and thousands of prisoners. They came back through our dugouts and they were absolutely demoralised. We were all so happy we didn't know what to do! Then, when we got a look at the craters, we saw there were lumps of blue clay as big as small buildings lying about. Our Hill 60 crater was a hundred yards across from lip to lip and forty-five yards deep, although a lot of the stuff had naturally fallen back into the crater. We thought the war was over."
The Spanbroekmolen Mine was the largest of the 19 mines set off at the beginning of the Battle of Messines on 7th June 1917. Work began on this mine in December 1916 and continued until shortly before the time it was detonated. In February 1917 German counter-mining damaged the main tunnel and a great deal of work was needed to drive forward a new tunnel in time for the planned assault. In the hours prior to its detonation this mine was loaded with a charge of 91,000 lbs of Ammonal.
At 03:10 hrs on 7th June 1917 the British detonated 19 mines of the 25 mines simultaneously. It was the detonation of so many mines at one time that resulted in the catastrophic effect on the German frontline positions. The simultaneous impact of so many explosions rendered not only those troops directly above the mines incapable of any resistance, when they were flung bodily up into the sky or just blown to bits, but the scale of the devastation around those not bodily affected so shocked them that many were left incapacitated anyway.
The sound of the 19 mine explosions was heard in London and some say as far away as Dublin. It was considered the loudest man made sound up to that point. The Spanbroekmolen Mine exploded 15 seconds later than the others. The reason why this happened is unknown, but the men of the 36th (Ulster) Division were already advancing towards the enemy frontline when it went up. They had been instructed to advance even if the mines did not explode and as a result many of the 52 soldiers of the Royal Irish Regiment buried in the nearby Lone Tree Cemetery fell victim to the explosion.
The Attack Goes In
In the south on the right of the II ANZAC Corps' area the 3rd Australian Division commanded by Major General John Monash moved up in the area of Ploegsteert. As they came through Ploegsteert Wood they were shelled by the German Artillery firing gas rounds and lost around 500 of their men. The mines went off as they reached their line of departure and they had to go straight into the attack. The Germans, however, put up little resistance and those that the Australians encountered were so shocked and confused that they were beyond resisting.
In the centre of the II ANZAC Corps' area the New Zealand Division made swift progress towards Mesen, but the mine in the area of Petit Douve Farm was one of those that failed to detonate. The village of Mesen was almost completely demolished by the British preparatory artillery barrage, but the Germans had made use of the cellars. As the barrage lifted they crawled out of their hiding places into the rubble of the village that provided excellent cover for their machinegun positions and men. After two and a half hours of fighting Mesen and the trenches on the hill to the east were in the New Zealander's hands. The Germans had put up a stiff fight but had proved unequal to the tanks and men from down under. During this assault Brigadier Brown, the commander of the 1st New Zealand Brigade, was killed by shellfire.
Following behind the assault of the New Zealand Division and 3rd Australian Division for the second phase of the attack during the Battle of Messines at the southern end of the battlefield was Major General William Holmes' 4th Australian Division. Their role was to to capture the Oostaverne Line in their area and the German Artillery Batteries that were supposedly to the west of it.
On the left of II ANZAC Corps the British 25th Division assaulted the German stronghold of Ontario Farm. This should have been the site of the mine. The tunnelling had initially been started along the site of an old river bed, but this had proved to be too wet and the mine had to be restarted further back. By the time of the attack it had not been extended to the full distance and only reached under the German frontline trenches. When this mine was set off a large crater was created, but it had little depth because "the wet sand flowed back almost as if it had been exploded in treacle."
On the right of the IX Corps area the 36th (Ulster) Division advanced against one of the heaviest defended sectors of the German line near the village of Wijtschate. This was why there were a greater number of mines in the area; the Kruisstraat group, Peckham mine and the massive mine at Spanbroekmolen. The Spanbroekmolen mine had only been finished the day before the assault and it detonated slightly later than the others. Unfortunately the Ulstermen were already out of their trenches attacking when this happened and a number of them were killed. The crater left behind by the Spanbroekmolen mine was the largest of them all and is today filled with water. This pool is called the pool of peace. The Ulstermen went on to capture an entire German Battalion headquarters before eventually coming up alongside of the 16th (Irish) Division.
The 16th (Irish) Division attacked against the village of Wijtschate. The village had been heavily defended by the Germans, but the Irish achieved their mission with relative easy due to the impact of the mine at Maedelstede Farm and the twin mines at Petit Bois. One of those killed during this attack was Captain James Patrick Roche MC, a trench mortar officer from the 47th Trench Mortar Battery.
On the left of IX Corps was the 19th Division attacked the Grand Bois. They met no resistance from the Germans at all as the Hollandscheschur group of mines had obliterated the German trenches. Those Germans that survived either fled or surrendered as the 19th Division approached. At the Grand Bois the 19th also met with no resistance, the German positions had been shelled with incendiary and gas rounds and those defenders that were left made no fight of it at all.
On the right of X Corps was the 41st Division who were attacking over the battlefield of St Eloi. The 1st Canadian Tunnelling Company had dug the deepest of the mines in this area which they had charged with nearly 100,000 lbs of ammonal. The effect of the explosion was impressive, the whole German frontline and the stronghold defending it was obliterated. The Canadian engineers were said to be disappointed by the size of the crater it made.
To their left was the 47th Division who had no mines in their area at all, but when they attacked they crossed the 300 yards or so of no mans land in less than 15 minutes. The devastating effect of the mines either side had, however, taken their toll on the German defenders who surrendered as the 47th Division advanced.
The most northerly unit of the attack was the 23rd Division who were tasked with taking Hill 60. Hill 60 and the corresponding spoil heap on the other side of the railway were both mined and when detonated the German positions were reduced to rubble. Hill 60 was once again in British hands.