On 9 October, following the success of the fighting at Broodseinde on the 4th October, the British 49th and 66th Divisions of Lieutenant General Godley’s II ANZAC Corps, attacked Passchendaele, supported on the right by 2nd Australian Division of Lieutenant General Birdwood’s I ANZAC Corps. This preliminary operation became known as the Battle of Poelcappelle. It was not palatable to the British to call it the Battle of Passchendaele, due to the complete failure of the attack on Passchendaele itself, the main objective. Since 5th Army’s flanking attack at Poelcappelle achieved greater success, the battle was named after this supporting effort.
Due to the continual rain since Broodseinde (4 October), the impassability of the ground meant that only part of the artillery had been brought forward in the four days between the battles. There was insufficient time to prepare gun positions, and many guns sank in the mud and were therefore unusable. Likewise, adequate ammunition could not be brought forward to the gun line. Transport from the duckboards to the gun positions was by pack animals, many of which sank into the quagmire, and often neither they nor their loads could be recovered. Ammunition which did make it to the gun line had to be cleaned of mire before it could be used.
In these conditions neither the preparatory bombardment nor the protective barrage could be fired effectively. The enemy front line and artillery positions were therefore not effectively suppressed either before or during the attack. Charles Bean wrote: “I suspect that they are making a great, bloody experiment – a huge gamble.”
The Infantry were exhausted by their tortuous approach marches through the mud, and then had to drag themselves forward through the quagmire to assault the unsuppressed German machine-guns. 66th Division in the centre and 2nd Division on the right took their first objectives in the face of feeble front line enemy resistance and pressed on to their second objectives, but then had insufficient strength to hold them in the face of determined German counter-strokes.
It was this German tactic of absorbing the first wave of an attack and then vigorous counter attacking that General Plumers "bite and hold" tactics had been developed to counter. The aim was to be in position to smash the inevitable counter attacks. But with the foundations awry there was not enough 'bite' to enable consolidation and 'hold' anything of consequence.
49th Division on the left failed in its attack, due to wire which was not cut and pillboxes which were not suppressed by the ineffective preparatory bombardment. 66th Division, being enfiladed by machine gun fire from Bellevue Spur, had to withdraw to its start line, and likewise 2nd Division had to abandon the Keiberg Spur (near Celtic Wood).