• The Canal d'Aire, running West-East (often referred to as the La Bassée Canal)
• The village of Cuinchy, where there was a bridge (the 'Pont Fixe') across the canal
• The Bethune to La Bassée road, running roughly parallel with the canal through the village of Cambrin and just to the north of the miners community of Auchy-les-la-Bassée, now called Auchy-les-Mines
• The Brickstacks; great regular stacks of the stock of a brick factory located to the South of the Canal, East of Cuinchy
• The villages of Vermelles, behind the British lines, and Hulluch behind the German
• The Bethune to Lens road, running South-East, with the mining community of Loos-en-Gohelle (from which the battle gets its name) just to the North of the road as it enters the outskirts of Lens. The village was dominated by the long dump of coal mine slag (the Loos Crassier), and towering pithead buildings.
• The mass of mining and industrial districts of Mazingarbe, Grenay, and Bully-le-Mines behind the British lines. South-East of Loos village, towards Maroc, the heights of the Double Crassier slag heap.
• The mining communities of Cité St Elie, Cité St Auguste and Cité St Laurent, behind the German lines
• The mine works, railways and lifting gear dotted around the battlefield. Note: the mine pits are called Puits, and are numbered in this area by the local mining company; the heaps alongside them are called Fosses. Most important areas included the dump at Fosse 8, in front of Auchy, and the Quarries in front of Hulluch. Both positions were strongly fortified by the enemy, the one at Fosse 8 being called the Hohenzollern Redoubt.
• East of Loos, the ground rises gently to a height of 70 feet: not much but a point of observation advantage in this area.

Joffre's plan was brutally simple. The strong enemy positions would be crushed by 4 days continuous bombardment, with a 4-hour final crescendo before the infantry attacked. The latter would be arrayed in great depth, each Division placing no more than half of two Brigades in the first line. A constant flow of men would follow, as would the reserves behind the assaulting Divisions. All other Armies from the coast to Switzerland would be ready to move forward as the enemy were destroyed in Artois.

Sir John French arranged for Second Army to carry out subsidiary attacks near Ypres, as would First Army North of the La Bassée canal in addition to their main assault role.

75,000 British infantry would make the initial attack. Experience at Neuve Chapelle and Festubert had shown that troops attacking on a narrow front would suffer from concentrated fire. First Army therefore made their attack front as wide as possible, placing all six Divisions of I and IV Corps in line, but faced the dilemma that the numbers and weight of heavy artillery they had available was insufficient to support such a breadth of front. It was decided to use intense smoke barrages to conceal the front as far as possible, and also to employ Chlorine gas for the first time as a means of compensating for the relatively lightweight artillery. Final detailed orders were issued by First Army on 19th September. Much secrecy was maintained about the use of gas; the word 'accessory' was substituted in all orders.

"Lt-Col Fowkes called on me from GHQ regarding the use of asphyxiating gas. I said better wait until we can use it on a large scale, because the element of surprise is always greater on the first occasion." Sir Douglas Haig, 7 July 1915

The divisions of the General Reserve were to be held North and South of Lillers, under orders of the Commander-in-Chief. They were: Cavalry Corps 1st, 2nd and 3rd Cavalry Divisions, and XI Corps, the Guards, 21st and 24th Divisions. The latter two formations had very recently arrived in France and had not yet seen the trenches. The infantry units began moving from St. Omer on 20th September, with marches of over 20 miles throughout successive nights. Sir John French instructed Sir Douglas Haig to prepare the attack plan on the basis that two divisions of the reserve would be placed at his disposal when required. Haig planned to use 21st and 24th Divisions as an immediately-available reserve, which enabled him to use all six of his existing Divisions in the front-line assault. He assured his Corps commanders that ample reserves would be available to reinforce or exploit successes. But by 18th September Haig had learned of French's intentions to keep the reserves at Lillers, some 16 miles from the battle front. He protested, citing the experiences of Neuve Chapelle and Festubert, where it was clear that reinforcements were needed within perhaps three hours of start. General Foch advised that 2000 yards would be a more suitable distance. French, since Neuve Chapelle acutely conscious of the threadbare supply of men, munitions and equipment, would not agree. He did, however, give orders that by dawn on the day of assault, the heads of the 21st and 24th Divisions should be at Noeux-les-Mines and Beuvry respectively, with the Guards Division following up. On 24th September the reserve divisions were warned to carry extra rations as it may be some time before their cookers caught up with them. They also carried greatcoats on the march to the battle area, which began at 7.00pm that night.

Medical facilities on the First Army front at Loos included 16 Advanced Dressing Stations, 15 Main Dressing Stations and 13 Casualty Clearing Stations (the latter at Lapugnoy, Lozinghem, Chocques, Bethune, Lillers (3), Aire (2), Merville (3) and St. Venant). In all, these units could accommodate just over 11,500 casualties at any time. 17 ambulance trains were also provided, as were barges and road transport to evacuate wounded men towards the coast. In all, arrangements were made to cope with 40,000 casualties.

Squadrons of the Royal Flying Corps would fly missions to bomb German railway and other communications, in addition to their vital artillery reconnaissance.