The Battle of Messines (7–14 June 1917)
The 19 mines beneath the German lines destroyed the German front line defences. Immediately after the detonation 9 Divisions of the British Second Army, under the command of General Sir Herbert Plumer, started the Battle of Messines.
Five German Divisions of the “Gruppe Wijtschate” of the 4th Army under General Friedrich Sixt von Armin defended the front sector on the heights, later reinforced by a division from the “Gruppe Ypern”. The "Gruppe Wijtschate" comprised units of the IX Reserve Corps, the 204th, 35th, 2nd, 3rd Bavarian and 4th Bavarian divisions, supported by the 7th Division and 1st Guards Reserve Division.
The objectives of the attack at Messines were to capture the high ground south of Ypres from the German defences on Messines Ridge and to shorten the allied front line, and so to gain a better starting position for the follow-up of the Third Battle of Ypres.
Preliminary Artillery Bombardment
On 8 May 1917, a month before the mine detonation, the British preliminary artillery bombardment had already started on the front between Hill 60 in the north and Ploegsteert in the south. From 23 May the bombardment intensified. During the week before the attack, 2,230 British guns and howitzers bombarded the German trenches, cut wire, destroyed strongholds and conducted counter-battery fire against 630 German artillery guns, using 3,561,530 shells.
On 7 June at 2:50 AM, the preliminary artillery bombardment ceased. The German defenders left their dug-outs and returned to their forward trenches, awaiting a customary follow-up of an infantry attack.
At 3:10 AM the mines exploded, killing some 10,000 German soldiers and paralysing the astonished survivors.
Creeping Barrage - Infantry Attack - Tanks - Air Support
A creeping artillery barrage of 640 m. deep followed the mine detonations. This barrage covered the infantry units of New Zealand, Australia, and Ireland as they attacked the front line with support from 72 Mark IV tanks and 300 aircraft.
In the north, the 16th (Irish) Division attacked between Maedelstede Farm and the Vierstraat–Wijtschate road. In Wijtschate and near St. Eloi, some German units held out, waiting to be relieved by counter-attacks which never arrived.
(Map above: US Military Academy of West Point)
In this area of Messines the 36th (Ulster) Division was helped by the mine at Peckham Farm, which devastated the area. The survivors were stunned by the mine explosion. The 36th (Ulster) Division’s attack was also supported by the 2 mines at Kruisstraat and the mine at Spanbroekmolen.
Members of both Divisions captured the German lines hardly without resistance and occupied the village of Wijtschate.
II Anzac Corps
The II Anzac Corp’s objective was the southern part of the ridge and Messines village. In the sector of II Anzac Corps mines detonated at Ontario Farm and near Ploegsteert and St. Yvon at Trench 122 and 127. The British 25th Division, attached to II ANZAC Corps, advanced on the left flank of the Corps.
On the right flank, the 3rd Australian Division attacked between St. Yvon and the Douve brook. The New Zealand Division approached in the middle from the south-west over Hill 63 and avoided a German gas bombardment.
The attacking brigades crossed the Steenbeke brook and the Douve brook and took the German front line at La Petite Douve Farm. From there the brigades advanced towards Messines village.
During the creeping barrage the German defenders only saw dust and smoke, being simultaneously under fire from British tanks and artillery and being machine-gunned from aircraft. Still the German defence on Messines Ridge answered these attacks with heavy machine gun fire causing many British casualties, soldiers from Ulster, Ireland, New Zealand and Australia. Finally the resistance in the south collapsed, forcing the Germans to retire to the east, to the “Sehnen Linie” or Oosttaverne line running from Hollebeke in the north to Warneton in the south.
(Map above: Battle operations of 7-11 June 1917. The dark grey sector indicates the ground, captured by the British.)
On 14 June, after the battle, the British had 24,582 casualties. The Germans counted about 35,000 casualties, including 10,000 soldiers Missing In Action or made Prisoner Of War (7,200).
Military historians do not agree on the strategic significance of the battle. Although the casualty numbers of wounded and killed soldiers of both parties are roughly in balance, after all the British operation was a success. The British divisions reached almost all their battle objectives and gained terrain on strategic heights. The operation shortened the allied font line to facilitate the next battle in the area. The Battle of Messines was a rather short prelude to the much longer offensive of a month later, the Third Battle of Ypres of July 1917.