The attack took place 9.9 mi (16 km) from Lille, between the Fauquissart–Trivelet road and Cordonnerie Farm, an area overlooked from Aubers Ridge to the south.

The advance took place in daylight, on a narrow front, against defences overlooked by Aubers Ridge, with German artillery on either side free to fire into the flanks of the attack.

Another attack by the 61st (2nd South Midland) Division early on 20 July was cancelled, after it was realised that German counter-attacks had already forced a retirement by the Australian troops to the original front line.

The attack was the début of the AIF on the Western Front and the Australian War Memorial described it as "the worst 24 hours in Australia's entire history".

The First and Second army commanders were required to choose places to penetrate the German defences, if the attacks on the Somme continued to make progress.

Haking was ordered to begin a big preliminary bombardment to simulate a large offensive and conduct a local infantry attack on the German front line.

The twelve attacking battalions were supported by more artillery than the Battle of Aubers Ridge in May 1915, more ammunition was available and there were trench mortars for wire cutting.

The fortification programme had several opponents, notably the 6th Army commander Crown Prince Rupprecht, who claimed that a rear position would undermine the determination of soldiers to stand their ground.

After a British gas attack opposite Neuve Chapelle and Fauquissart late on 15 July, German artillery bombarded the British front line and a raid on the Australian lines by 100 troops of Bavarian Reserve Infantry Regiment 21, caused nearly 100 casualties, taking three prisoners, for a loss of 32 casualties.

It was hazy early on 19 July but the artillery zero hour was fixed for 11:00 a.m., ready for the attack at 6:00 p.m. A special heavy artillery bombardment began on the Sugarloaf at 2:35 p.m., by which time a German counter-bombardment was falling all along the attack front, causing casualties to the Australians and the field gunners of the 61st (2nd South Midland) Division at Rue Tilleloy.

Uncut wire held up the advance to the second line and German machine-gun fire from the right flank caused many casualties as the survivors reached the objective.

The attack of the left-hand battalion towards the Sugarloaf salient (which was beyond trench-mortar range) was stopped by German fire on the sally ports; the British tried to exit along "Rhondda Sap", which was under shrapnel bombardment.

Reinforcements with equipment and tools went forward and work began on a communication trench across no man's land in the midst of a German artillery barrage and movement attracting machine-gun fire.

More discussion between Mackenzie and Haking led to the corps commander ordering the 184th Brigade to attack the Sugarloaf overnight, after a ten-minute hurricane bombardment; German shelling on the British front line then caused a postponement until the morning.

Consolidation in the German lines was slow as the troops lacked experience, many officers had become casualties and there was no dry soil to fill sandbags, mud being a poor substitute.

[21] News of the retirement by the 8th Australian Brigade reached McCay while at a meeting with Mackenzie, Haking and Monro, to plan the new attack by the 61st (2nd South Midland) Division.

German troops had got well behind the right flank and fired at every sign of movement, forcing the Australians to withdraw along the communication trench dug overnight.

[22] From 14 July the Illies–Beaucamps road, 3 mi (4.8 km) behind the German front line, was kept under air observation by the Royal Flying Corps (RFC).

[23][e] Army squadrons flew further afield and denied German reconnaissance aircraft view of British troop movements, particularly behind the XI Corps front.

On 19 July, aircraft from two squadrons patrolled the area towards Lille and had numerous air engagements, in which two Fokker E.Is and a British DH.2 were shot down.

Bombing raids on German army billets, supply dumps and the railways from Lille to Lens, Douai, Cambrai and Valenciennes also took place.

The British entered the front line for the first time on 13 June and every man not due to participate in the attack spent from 16 to 19 July removing poison gas cylinders from the front line after the discharge planned for 15 July was suspended due to the wind falling; 470 cylinders were removed before the work was stopped because the men were exhausted.

[31] A German assessment of 16 December, called the attack "operationally and tactically senseless" and that prisoner interrogations revealed that the Australian troops were physically imposing but had "virtually no military discipline" and "no interest in soldiering as it was understood in Europe".

In his 2012 biography of Haking, Senior wrote that he had only consulted the official history volume Military Operations France and Belgium, 1916 part II for his earlier book and had changed his mind after studying German records.

Had divisions moved earlier, the Battle of Pozières (23 July – 3 September), might have cost I Anzac Corps far more than the 23,000 casualties that it suffered.

In 2002, Lambis Englezos was inspired by Don't Forget Me Cobber (Corfield, 2000), to search for an unmarked mass grave near Fromelles.

The site was found by Englezos and other researchers near Fromelles at le bois au fond du village, Fasanenwäldchen (Pheasant Copse/Pheasant Wood) (50°36′36.36″N 2°51′17.10″E / 50.6101000°N 2.8547500°E / 50.6101000; 2.8547500).

From 23 May to 13 June 2008, an exploratory dig found human remains, personal effects, webbing, brass fitments, uniform badges, buttons and .303 British ammunition in five of six pits, which were then refilled.

[57] The plaque in it pays tribute to the pioneering work of Robin Corfield and Lambis Englezos in gaining wider attention to the battle and the loss of life of so many Australians, as well as British soldiers.

[58] In 2016, plans to hold a memorial event at the Pheasant Wood military cemetery were announced with the controversial decision to exclude British attendees from the ceremony.