When the first shells passed overhead and the mines were fired at 4:15 a.m. on 27 March, it "appeared as if a long village was being lifted through flames into the air" and "there was an earth shake but no roar of explosion".
The detonation obliterated the Mound and the trenches rocked and heaved, burying about 300 men of RJB 18, which had partly withdrawn into the reserve line as a precaution.
The British heavy artillery fired a barrage along the flanking trenches and behind the salient, varying the area periodically.
Infantry advanced quickly, ignoring the half-minute delay for flying débris and found that mines 2, 3, 4 and 5 had gone off under the German front and support lines, demolishing the defences.
Mine 1 had exploded in no man's land on the right flank, forming a crater to defend it.
Mine 6 had done the same on the left flank and also blown up a German grenade throwing post.
The Northumberland Fusiliers advanced and lost only one man before reaching the German wire, finding that the German survivors were ready to surrender.

The Royal Fusiliers were hit by machine-gun fire from the left flank as they climbed the parapet; a German counter-barrage on the front line began only 40 seconds after the Northumberland Fusiliers attacked and continued nearly all day.
The Royal Fusiliers only reached part of a German trench south of craters 4 and 5 on the right flank and the junction with the Northumberland Fusiliers but left a gap.
The Royal Fusiliers were at crater 6 and an older crater to the east, the topography of the area having changed so much that it was hard to orientate.
Consolidation was slowed by the German artillery-fire; working and carrying parties of the 1st Royal Scots Fusiliers and the 12th West Yorkshires from the 9th Brigade had many casualties.
The Germans' deep drainage system had gone up with the mines, the trenches began to flood as intermittent showers turned into a downpour.
The British troops were replaced frequently; despite their tiredness, battalions were poached from resting brigades to make up the numbers.
Over the night of 27/28 March the 13th King's, 2nd Royal Scots and the 8th East Yorkshire from the 8th Brigade relieved the 1st Northumberland Fusiliers, 4th Royal Fusiliers and the 1st Royal Scots Fusiliers.
On the night of 28/29 March the exhaustion of the troops led to the 2nd Suffolk and 10th Royal Welsh Fusiliers relieving two more 8th Brigade battalions and a company of the 18th Canadian Battalion from the 4th Canadian Brigade relieved the 12th West Yorkshires, the last of the 9th Brigade battalions. (
In the morning an apparent German counter-attack turned out to be a surrender attempt.)
When the first shells passed overhead and the mines were fired at 4:15 a.m. on 27 March, it "appeared as if a long village was being lifted through flames into the air" and "there was an earth shake but no roar of explosion". The detonation obliterated the Mound and the trenches rocked and heaved, burying about 300 men of RJB 18, which had partly withdrawn into the reserve line as a precaution. The British heavy artillery fired a barrage along the flanking trenches and behind the salient, varying the area periodically. Infantry advanced quickly, ignoring the half-minute delay for flying débris and found that mines 2, 3, 4 and 5 had gone off under the German front and support lines, demolishing the defences. Mine 1 had exploded in no man's land on the right flank, forming a crater to defend it. Mine 6 had done the same on the left flank and also blown up a German grenade throwing post. The Northumberland Fusiliers advanced and lost only one man before reaching the German wire, finding that the German survivors were ready to surrender.
The Royal Fusiliers were hit by machine-gun fire from the left flank as they climbed the parapet; a German counter-barrage on the front line began only 40 seconds after the Northumberland Fusiliers attacked and continued nearly all day. The Royal Fusiliers only reached part of a German trench south of craters 4 and 5 on the right flank and the junction with the Northumberland Fusiliers but left a gap. The Royal Fusiliers were at crater 6 and an older crater to the east, the topography of the area having changed so much that it was hard to orientate. Consolidation was slowed by the German artillery-fire; working and carrying parties of the 1st Royal Scots Fusiliers and the 12th West Yorkshires from the 9th Brigade had many casualties. The Germans' deep drainage system had gone up with the mines, the trenches began to flood as intermittent showers turned into a downpour. The British troops were replaced frequently; despite their tiredness, battalions were poached from resting brigades to make up the numbers. Over the night of 27/28 March the 13th King's, 2nd Royal Scots and the 8th East Yorkshire from the 8th Brigade relieved the 1st Northumberland Fusiliers, 4th Royal Fusiliers and the 1st Royal Scots Fusiliers. On the night of 28/29 March the exhaustion of the troops led to the 2nd Suffolk and 10th Royal Welsh Fusiliers relieving two more 8th Brigade battalions and a company of the 18th Canadian Battalion from the 4th Canadian Brigade relieved the 12th West Yorkshires, the last of the 9th Brigade battalions. (In the morning an apparent German counter-attack turned out to be a surrender attempt.)
Actions of St Eloi Craters