The advance was planned to cover 1,000–1,500 yd (910–1,370 m) and stop on reverse slopes, which were easier to defend, enclosing ground which gave observation of German reinforcement routes and counter-attack assembly areas.

The mist cleared during the morning and revealed German Eingreif (counter-attack) formations to air and ground observation, well in advance of their arrival on the battlefield.

A pause in British attacks was used to reorganise and to improve supply routes behind the front line, to carry forward 54,572 long tons (55,448 t) of ammunition above normal expenditure.

The unseasonal rains stopped, the ground began to dry and the cessation of British attacks misled the Germans, who risked moving some units away from Flanders.

[8] The offensive had resumed on 20 September with the Battle of the Menin Road Ridge, using similar step-by-step methods to those of the Fifth Army after 31 July, with a further evolution of technique, based on the greater mass of artillery made available to enable the consolidation of captured ground with sufficient strength and organisation to defeat German counter-attacks.

The I Anzac Corps (Lieutenant-General William Birdwood) would conduct the main advance of about 1,200 yd (1,100 m), to complete the occupation of Polygon Wood and the south end of Zonnebeke village.

Roads and light railways were built behind the new front line to move artillery and ammunition forward, beginning on 20 September; in fine weather this was finished in four days.

Heavier equipment bogged in churned mud so had to be brought forward by wagons along roads and tracks, many of which were under German artillery observation from Passchendaele ridge, rather than being moved cross-country.

[18] The German defensive system had been more effective in the unusually rainy weather in August, making movement much more difficult and forcing the British to keep to duckboard tracks, easy to identify and bombard.

The leading waves of infantry were lightly equipped, further apart and followed by files or small groups ready to swarm around German defences uncovered by the skirmish lines.

The proportion of smoke ammunition for rifle grenades and Stokes mortars was increased, to blind the occupants of German pillboxes as they were being surrounded.

The main attack was to be conducted by the I Anzac Corps with the 5th and 4th Australian divisions on the remainder of Polygon Wood and the southern part of Zonnebeke village.

[37] Crown Prince Rupprecht had ordered the attack to recover ground on the Gheluvelt Plateau and to try to gain time for reinforcements to be brought into the battle zone.

Return-fire from the 33rd Division troops under attack and the 15th Australian Brigade along the southern edge of Polygon wood, forced the Germans under cover after they had recaptured several pillboxes near Black Watch Corner.

In the 15th Australian Brigade the battalions were to advance successively but bunched up near the first objective and were stopped by pillboxes at the "racecourse" and fire from the 33rd Division area to the south.

A reserve battalion overran the dugouts and more pillboxes nearby, advancing to just beyond the final objective, at the junction with the 4th Australian Division to the north, taking 200 prisoners and 34 machine-guns.

The brigade reached the final objective from just short of the Flandern I Stellung on the right and the edge of Zonnebeke on the left and gained touch with the 5th Australian Division further south.

A bigger attempt at 6:30 p.m. was defeated with rifle and machine-gun fire, as the British attack on Hill 40 resumed, eventually leaving both sides still on the western slope.

A German counter-attack between 5:30 p.m. and 6:50 p.m. pushed back some advanced posts, which with reinforcements were regained by 11:00 p.m.[52] In the XVIII Corps area, the 58th (2/1st London) Division attacked with one brigade at 5:50 a.m.

[54] Aircraft of the Australian Flying Corps (AFC) flew over the infantry on contact patrol, the aeroplanes being distinguished by black streamers on the rear edge of their left wings.

The crews called for signals from the ground by sounding a klaxon horn or dropping lights, to which infantry responded with red flares to communicate their position to be reported to the Australian divisional headquarters.

[46] The Royal Flying Corps (RFC) began operations on the night of 25–26 September when 100 and 101 squadrons attacked German billets and railway stations.

Mist rose before dawn and ended night flying early; low cloud was present at 5:50 a.m. when the infantry advanced, which made observation difficult.

The companies south of Zonnebeke advanced and were overrun by British troops on the Grote Molen (Large Mill) spur and taken prisoner.

Observation aircraft found German troops massing against Tower Hamlets, on the Bassevillebeek spur and artillery and machine-gun barrages stopped the attack before it reached the British infantry.

[64] British counter-attack patrols easily observed the advance and as the lines of German troops breasted Broodseinde ridge at 2:30 p.m., a huge bombardment enveloped them.

[68] Albrecht von Thaer, the Chief of Staff of Gruppe Wijtschate (the XII Saxon Corps headquarters) made a diary entry on 28 September that "We are living through truly abominable days" and that he had no idea what to do about the British limited-objective attacks and their devastating artillery support.

The effort made by the Germans to hold the ground captured on 25 September at the Reutelbeek and south of Polygon Wood showed the importance of the upper ends of the valley between Becelaere and Gheluvelt.

The Germans could be expected to defend the Zandvoorde Ridge north of Becelaere with even greater determination to prevent the British from gaining observation over the assembly areas beyond it to the east.

Joist Farm was lost by the 21st Division during a German attack on Polygon Wood and Black Watch Corner and the line stabilised east of Cameron House.