Did the nineteen British mines detonated at the start of the Battle of Messines really result in the death of 10,000 German soldiers? Or did the British attack positions from which the Germans had already withdrawn? These contrasting assertions have both been made in respect of the week-long Battle of Messines which opened on 7th June 1917.
Many accounts attest to the shock and panic caused among the Germans by the detonation of the mines. The number actually killed is difficult to quantify but the astonishing claim that 10,000 Germans were killed by the explosions which has begun to appear in popular history sources clearly has to be questioned. The probable recent origin of this figure is a history of the battle published in 1998, which implied that, of 10,000 German soldiers missing after the battle, many ‘were undoubtedly vaporised or blown apart by the effects of the mines.’
The figure of 10,000 missing is from the German Official History which states that it covers a 21-day period ending on 10th June 1917. Furthermore, of this figure 7,200, according to British sources, were actually taken prisoner, reducing the number who were killed to 2,800. To this must be taken into consideration that many of the German casualties were caused the massive and highly effective British artillery barrages, rather than by the mine detonations.
Direct evidence of the casualties caused by the mines is given in the description by a mining engineer on the staff of the Inspector of Mines at GHQ, Major Ralph Stokes. He examined three of the mine craters on the day of the attack and attempted to establish how many men had been killed. The evidence was most clear at the Ontario Farm mine where, unusually, the debris had largely fallen back into the crater and not covered the surrounding area. Two concrete bunkers had been physically lifted into the air, one at the middle of the crater was buried but he managed to look into the second:
One at the side had contained 8 men, who were all lying in a lump, dead. (We saw these about noon. At 7am 2 were alive). One wore spectacles which were still on his nose.
Stokes noted that another man, of the 17th Bavarian Infantry Regiment, ‘was dying on the south side of the crater.’ Were the mine to have detonated as most of the others had, and thrown its debris more widely, Stokes believed that it would have buried a third dugout and caused more casualties. He believed that the bunkers were mostly occupied by small posts of four to eight men, which led him to estimate the number of Germans who lost their lives at each of the mines:
Judging from the dead seen around craters & distances between the posts, each of the five southern mines killed 10-20 men.
If Stokes’s estimate of 20 men killed at each crater is applied to all 19 mines, the result is just 380 killed, a dramatically lower number than 10,000. Even with the possibility that some parts of the German front line assaulted were more crowded, it is unlikely that the number was more than 500. The effect of the mines lay their shock value, disorientating the defenders and inducing panic.
Did the Germans withdraw from the Messines Ridge?
The claim that the Germans had withdrawn from the Messines Ridge originates with the historian Denis Winter in a superficially scholarly but heavily flawed study of the command of Sir Douglas Haig published in 1991. It appears to result from a fundamental misinterpretation of a discussion between British commanders just over week before the attack was launched whilst also disregarding a parallel debate among German commanders on the subject of withdrawal. Examination of this debate explains why the Germans held their front line trenches with comparatively small numbers of men.
The British discussion took place just over a week before the battle was to begin. At the end of May, Field-Marshal Sir Douglas Haig, the British Commander-in-Chief, was faced with the possibility of all the mines being rendered ineffective by a German withdrawal. The British obtained a German document giving clear information about new German defensive tactics in which they would temporarily abandon their front line and destroy an attack with a heavy artillery bombardment. The British realised that, to ensure the success of the attack, they would have to force the Germans to disclose the locations of as many of their concealed gun batteries as possible so that British artillery could destroy them before the attack was launched.
On 29th May Haig’s Chief of Staff, Lieutenant-General Kiggell, wrote to the commander of the Second Army, General Sir Herbert Plumer, whose forces were to make the attack. He informed him that Haig wished to meet the following day to consider a proposal to detonate the mines four days before the actual attack as a means of deceiving the Germans into bringing their guns into action, thus revealing prematurely the concealed batteries.
Plumer had no evidence of a German withdrawal from their front line: reports indicated that in places it was held in strength, in others by posts only. Nevertheless, his initial reaction was to agree with Haig; on consulting his corps and divisional commanders, Plumer was informed that they wished to follow the original plan. At the meeting with Haig, Plumer proposed dealing with the German tactics by prolonging by two days his artillery destruction fire and devoting the last two days before the attack entirely to counter-battery fire. To induce the German gun batteries to open fire he would simulate an attack by firing a complete false barrage. The new German tactics would be defeated by destruction of the German artillery. Haig supported Plumer’s plan and the premature blowing of the mines was ruled out. Bizarrely, Winter somehow interpreted the discussion in the British command as evidence that the Germans had actually evacuated from their forward positions at Messines Ridge.
As it happened, the Germans had reduced the number of men in their front line but a withdrawal at Messines had already been considered and rejected by senior German commanders, a month before Haig’s proposal. The instructions captured by the British related to a system of flexible defence in depth which was being adopted by the Germans. The Germans had found during the Battle of the Somme that their tactic of keeping large numbers of troops in their forward positions rendered them too vulnerable to capture by attackers following closely behind artillery barrages. Instead, the Germans proposed to hold the forward line with just a few men, so that the attackers had to advance beyond the range of their field artillery before encountering the main body of defenders. As they advanced, the attackers would be destroyed by the German artillery, after which the counterattack troops advanced to retake the lost positions.
Persuading commanders to adopt such a system of defence however was not easy, and required both a considerable mental readjustment and the scrapping of defences which had taken years to construct. On 30th April, the Chief of Staff of the Army Group commanded by Prince Rupprecht of Bavaria, Lieutenant-General von Kühl, asked Generals von Armin (4th Army) and von Laffert (XIX Corps, Gruppe Wytschaete) to consider withdrawal from the Messines Ridge in view of an expected attack. They rejected the proposal and subsequent enquiries concluded that neither of the defensive lines immediately behind the ridge were suitable; an investigation by the Army Group reported on 3rd May that the existing defences on the ridge could be defended, provided the artillery was kept sufficiently close to it.
A major factor for the Germans as to whether the position should be held was the likelihood of underground attack. The danger of British miners tunnelling beneath the ridge, regarded as a threat early in 1917, does not seem to have been considered as serious at this time; on 24th May the commander of mining troops in the German 4th Army, Lieutenant Colonel Füsslein, reported that the danger of mine attack had been averted by his countermeasures.
General von Kühl later regretted that he had not overruled the subordinate commanders and withdrawn from the Messines ridge:
It was a mistake of the Army Group command that it did not, in spite of all the objections, simply order evacuation. The German army would have been spared one of the worst tragedies of the world war.
 Ian Passingham, Pillars of Fire, (Stroud, 1998), pp. 162-3.
 Oberkommando des Heeres, Der Weltkrieg 1914 bis 1918, Vol. 12, (Berlin, 1939), pp. 471-2.
 Op. cit., pp. 469, 471.
 Maj. R. S. G. Stokes RE Visits Diary, 7-8/8/1917, TNA WO158/137.
 Op. cit.
 Denis Winter, Haig’s Command, (London 1991), pp. 96, 340.
 Letter Lt.-Gen. L. E. Kiggell to Gen. Sir H. C. O. Plumer, 29/5/1917; Summary of Proceedings of a Conference held at Pernes at 11am, 30th May, 1917, Lt.-Gen. L. E. Kiggell, 31/5/1917 (OAD464). Both documents in file ‘Messines – Wytschaete’, TNA, WO158/215.
 Winter interprets British knowledge of the German tactics as an actual German withdrawal comparable to that carried out to the Hindenburg Line during February to March 1917, citing Kiggell’s letter to Plumer 29/5/1917 (OAD464). This leads Winter to claim that the attack was against ‘almost empty German positions’ and that the British ‘advanced into a killing-ground on which pre-ranged German artillery smashed the attackers’, Winter, op. cit., pp. 96, 340; John Mosier, The Myth of the Great War, (London, 2001). pp. 282, 287 repeats a variant of this, citing Winter as his source.
 Oberkommando des Heeres, Der Weltkrieg 1914 bis 1918, op. cit., pp. 428-430, 433, 468-469.
 „Es war ein Fehler des Oberkommandos der Heeresgruppe, daß es nicht trotz aller Einwendungen die Räumung einfach befahl. Eine der schlimmsten Tragödien des Weltkrieges wäre dem deutschen Heere erspart geblieben.” General der Infanterie Hermann von Kühl, Der Weltkrieg 1914-1918, (Berlin, 1933), vol. 2, p. 114, quoted in Oberkommando des Heeres, Der Weltkrieg 1914 bis 1918, op. cit., p. 475.