There is an often-repeated claim that many of the British soldiers buried in a cemetery on the Messines Ridge battlefield were killed by the falling debris of their own mine, 150 yards away at Spanbroekmolen. What is the truth behind this claim?
The signal for the advance at the Battle of Messines was the detonation of nineteen mines, to be fired at Zero Hour at 3.10am on 7th June 1917. The decision to fire them exactly at Zero, rather than to allow time for the debris to fall, resulted from a disastrous error made at the opening of the Battle of the Somme on 1st July 1916, when one of the mines was fired ten minutes in advance and served to warn the German defenders in the entire sector of the imminent attack.
To fire the mines exactly at Zero was a risk. Although efforts were made to synchronise exactly the detonation of the Messines mines, in the event there was a delay of up to 30 seconds between the explosions. The first wave of attackers advancing to the Spanbroekmolen mine was comprised of men from the 14th Royal Irish Rifles but there are no eyewitness accounts from this unit to confirm that they suffered any loss from the mine. The after-action report by the battalion commander records confusion caused by the slight variation in the times of detonation. When a mine detonated, the men got up to attack from where they were lying ready in no man’s land but, as they advanced, another exploded in front of them, throwing them off their feet and causing them to lose direction in the dust and darkness.
The detonation of the Spanbroekmolen mine was also witnessed by an officer of the Tunnelling Companies, Major Ralph Stokes, who was at the tunnel entrance about 570 yards away. He recorded that the Peckham mine, 500 yards to the northeast, detonated 20 seconds before Spanbroekmolen. It seems therefore that the Peckham mine detonation caused the 14th Royal Irish to stand up and begin to advance only to be caught by the shock wave of the Spanbroekmolen. The absence of a reference to casualties from the Spanbroekmolen mine in the CO’s report does not mean that none occurred among the 14th Royal Irish.
However, the origin of the story of the Spanbroekmolen casualties may be traced to a widely-read book published in 1978, in which an account the attack on mines at Kruisstraat, 650 yards to the southeast, was confused with that on the Spanbroekmolen mine. In They Called It Passchendaele the author Lyn MacDonald quoted from an account by Lieutenant T. Witherow, 8th Battalion, Royal Irish Rifles, describing how his battalion also advanced prematurely (perhaps again owing to the Peckham mine firing before the others) and the death of a Lance-Corporal by falling mine debris:
We’d made it through the machine-gun fire and had almost got to the German positions, when a terrible thing happened that nearly put an end to my fighting days. All of a sudden the earth seemed to open and belch forth a great mass of flame. There was a deafening noise and the whole thing went up in the air, a huge mass of earth and stone. We were all thrown violently to the ground and debris began to rain down on us. Luckily only soft earth fell on me, but the Lance-Corporal, one of my best Section Commanders, was killed by a brick. It struck him square on the head as he lay at my side. A few more seconds and we would have gone up with the mine.
Witherow’s 8th Royal Irish at Kruisstraat was separated by another battalion from the 14th Royal Irish Rifles attacking at Spanbroekmolen. Stokes recorded that a group of three mines at Kruisstraat went off two seconds after the Spanbroekmolen mine (i.e. 22 seconds after the Peckham mine).  References in the text of They Called It Passchendaele indicate that Lyn MacDonald appeared unaware that Witherow’s battalion was far closer to the mines at Kruisstraat than to that at Spanbroekmolen. A footnote in the book to Witherow’s account compounds the error:
Many of the Irishmen, both Southerners and Northerners, who were killed by the fall-out from the Spanbroekmolen mine lie where they fell in tiny Lone Tree cemetery, just down the hill from the Spanbroekmolen mine crater.
Men of the 8th Royal Irish were indeed buried in Lone Tree Cemetery, even though they were killed some distance to the south, and it is quite possible that Witherow’s Lance-Corporal was buried there. No men from Northern Ireland, that is from the 36th (Ulster) Division, were killed by the Spanbroekmolen mine, the closest attackers being a third of a mile to the north. Unless further eyewitness accounts come to light, there is no evidence that more than one British soldier was killed by the debris falling at Kruisstraat, and none that any were killed at Spanbroekmolen.
 War Diary, 14th Battalion, Royal Irish Rifles, TNA WO95/2511.
 Maj. R. S. G. Stokes RE Visits Diary, 7-8/8/1917, TNA WO158/137.
 Lyn MacDonald, They Called It Passchendaele, (London 1978), pp. 46-7; the informant may be identified as Thomas Hastings Witherow (1890-1989). MacDonald does not give details of the source for the account but it may be a typescript memoir of which a copy is held in the Liddle Collection, University of Leeds https://library.leeds.ac.uk/special-collections-explore/30002/witherow_t_h.
 Maj. R. S. G. Stokes RE op. cit.
 MacDonald, op. cit., pp. 39-40, 46-7.
 MacDonald, op. cit., p. 47.