• Intelligence about the newly-strengthened Geman positions was not available, or given insufficient attention
• No surprise was achieved; the blowing of mines well before the attack placed the enemy on the alert
• Smoke screens were effective; cloud gas was not. It's behaviour proved unpredictable
• The duration and weight of the British bombardment was insufficient to break the German wire and breastwork defences, or to destroy or suppress the front-line machine-guns
• German artillery and free movement of reserves were insufficiently suppressed
• Trench layouts, traffic flows and organisation behind the British front line did not allow for easy movement of reinforcements and casualties
• British grenades were of poor design and manufacture, and were easily outranged by the enemy ones
• It soon became impossible to tell precisely where British troops were; accurate close-support artillery fire was impossible; RFC observation was very limited due to poor weather
• The New Army Divisions fought bravely but were clearly not yet trained to a sufficiently high fighting standard as a formation; they would need a period of familiarity with war conditions and could not be reliably deployed 'straight off the boat'
• The withdrawal of cookers to Divisional control was a disaster, with many men going hungry to battle

Major-General Sir T. Capper, OC 7th Division, fatally wounded near the Hulluch Quarries

Major-General Sir G. Thesiger, OC 9th Division, killed near the Fosse 8 Dump

Brigadier-General F. Wing, OC 12th Division, fatally wounded at Loos

British casualties in the main Loos front between 25 September and 16 October 1915
Formations that lost more than 5,000 men
15th (Scottish) Division: 6,896 of which 228 officers
9th (Scottish) Division: 6,058 of which 190 officers
1st Division: 6,030 of which 246 officers
7th Division: 5,224 of which 220 officers
Major infantry casualties, by battalion
What is a battalion?
Infantry battalions that lost more than 300 men (note: the typical attacking strength of a battalion at this time was 650-750)
7th Cameron Highlanders	687, of which 19 officers	Second wave of 44th Brigade, in Loos
9th Black Watch	680, of which 20 officers	First wave of 44th Brigade, in Loos
6th King's Own Scottish Borderers	650, of which 20 officers	First wave of 28th Brigade, in front of Auchy
10th Highland Light Infantry	648, of which 20 officers	First wave of 28th Brigade, in front of Auchy
7th King's Own Scottish Borderers	631, of which 20 officers	First wave of 46th Brigade, in Loos and on Hill 70
8th Devons	619, of which 19 officers	First wave of 20th Brigade, near Hulluch
8th Royal West Kents	580, of which 24 officers	72nd Brigade, attacking German second line near Chalk Pit
8th Buffs	558, of which 24 officers	72nd Brigade, attacking German second line near Chalk Pit
12th Highland Light Infantry	553, of which 23 officers	First wave of 46th Brigade, in Loos and on Hill 70
8th Black Watch	511, of which 19 officers	Reserve reinforcements of 26th Brigade, near Auchy
5th North Staffordshire	505, of which 20 officers	137th Brigade, at Hohenzollern redoubt, 13 October
8th Seaforth Highlanders	502, of which 23 officers	First wave of 44th Brigade, in Loos
8th Royal Berkshire	493	First wave of 1st Brigade, near Hulluch
1st Loyal North Lancashire	489	First wave of 2nd Brigade, near Hulluch
10th Scottish Rifles	485, of which 21 officers	First wave of 46th Brigade, in Loos and on Hill 70
5th Lincolns	483, of which 22 officers	138th Brigade, at Hohenzollern redoubt, 13 October
12th Northumberland Fusiliers	481, of which 22 officers	62nd Brigade, between Loos and Hulluch
2nd Royal Sussex	481	First wave of 2nd Brigade, near Hulluch
9th East Surrey	477, of which 22 officers	72nd Brigade, attacking German second line near Chalk Pit
1st Scots Guards	474, of which 14 officers	2nd Guards Brigade, at Puits 14 bis and Hill 70
4th Leicesters	473, of which 20 officers	138th Brigade, at Hohenzollern redoubt, 13 October
8th Lincolns	466, of which 12 officers	63rd Brigade, between Loos and Hulluch
15th Durham LI	462, of which 22 officers	64th Brigade, between Loos and Hulluch
2nd King's Royal Rifle Corps	460	First wave of 2nd Brigade, near Hulluch
10th Gloucesters	459	First wave of 1st Brigade, near Hulluch
1st Middlesex	455, of which 16 officers	First wave of 19th Brigade, on Cambrin road
1st South Staffordshire	448, of which 18 officers	First wave of 22nd Brigade, on Cite St Elie and Quarries
1st Royal Welch Fusiliers	442, of which 16 officers	Second wave of 22nd Brigade, on Cite St Elie and Quarries
8th Queens	439, of which 12 officers	72nd Brigade, attacking German second line near Chalk Pit
9th Norfolks	422, of which 12 officers	Reserve battalion, rushed into hasty counterattack at Hulluch Quarries
6th Buffs	409, of which 18 officers	37th Brigade, at Gun Trench, 13 October
6th South Staffordshire	407, of which 18 officers	137th Brigade, at Hohenzollern redoubt, 13 October
4th Lincolns	397, of which 10 officers	138th Brigade, at Hohenzollern redoubt, 13 October
13th Northumberland Fusiliers	396, of which 17 officers	62nd Brigade, between Loos and Hulluch
8th King's Own Scottish Borderers	383, of which 14 officers	Second wave of 46th Brigade, in Loos and on Hill 70
10th Gordon Highlanders	381, of which 7 officers	Second wave of 44th Brigade, in Loos
1/19th London	386, of which 14 officers	First wave of 141st Brigade, near Loos
1st Cameron Highlanders	387	Second wave of 1st Brigade, near Hulluch
9th Royal Sussex	379, of which 18 officers	73rd Brigade, in Fosse 8
7th Northamptonshire	377, of which 11 officers	73rd Brigade, in Fosse 8
11th Essex	371, of which 18 officers	71st Brigade, attacking German second line near Chalk Pit
2nd Highland Light Infantry	358, of which 8 officers	First wave of 5th Brigade, near Givenchy
2nd Argyll & Sutherland Highlanders	330, of which 15 officers	First wave of 19th Brigade, on Cambrin road
8th East Yorks	320, of which 21 officers	62nd Brigade, between Loos and Hulluch
10th Yorks and Lancs	319, of which 16 officers	63rd Brigade, between Loos and Hulluch
5th South Staffords	319, of which 13 officers	137th Brigade, at Hohenzollern redoubt, 13 October
1st Queens	317, of which 9 officers	First wave of 5th Brigade, near Givenchy
6th North Staffordshire	315, of which 17 officers	137th Brigade, at Hohenzollern redoubt, 13 October
12th West Yorkshire	314, of which 16 officers	63rd Brigade, between Loos and Hulluch
2nd Welch	311	3rd Brigade, in support near Hulluch
In addition, another 23 battalions lost more than 200 men

Senior officer casualties on or soon after 25 September 1915
Major-General Sir Thompson Capper, KCMG, CB, DSO	Officer Commanding 7th Division	Buried at Lillers Communal Cemetery
Major-General G H Thesiger, CB, CMG, ADC	Officer Commanding 9th Division	Commemorated on Loos Memorial to the Missing
Major-General F D V Wing, CB	Officer Commanding 12th Division	Buried at Noeux-les-Mines Communal Cemetery
Brig-General the Hon. J. Hepburn-Stuart-Forbes-Trefusis	Officer Commanding 20th Brigade	Buried at Guards Cemetery, Windy Corner, Cuinchy
Brig-General N. Nickalls	Officer Commanding 63rd Brigade	Commemorated on Loos Memorial to the Missing
Brig-General (Temp) F. Wormald	Officer Commanding 5th Cavalry Brigade	Buried at Nedonchel Churchyard Cemetery
Lt-Col. R. Dundas	OC 11/Royal Scots	Buried at Cabaret Rouge Cemetery
Lt-Col. G. Fowler	OC 8/Notts & Derbys	Buried at Fouquieres Churchyard Cemetery Extension after dying of wounds received at Hohenzollern Redoubt 15 October
Lt-Col. R. Garnons-Williams	OC 12/Royal Fusiliers	Commemorated on Loos Memorial to the Missing
Lt-Col. A. Grant	OC 8/Devonshire	Commemorated on Loos Memorial to the Missing
Lt-Col. A. Hadow	OC 10/Yorkshire	Buried at St Patrick's Cemetery, Loos
Lt-Col. A. Hamilton	OC 14/Durham LI	Buried at Hendon Park Cemetery, Middlesex after dying of wounds on 13 October 1915 received near Bois Hugo on 26 September 1915
Lt-Col. J. Knight	OC 5/North Staffordshire	Commemorated on Loos Memorial to the Missing
Lt-Col. E. Logan	OC 15/Durham LI	Commemorated on Loos Memorial to the Missing
Lt-Col. M. Heath	OC 2/Queens	Commemorated on Loos Memorial to the Missing
Lt-Col. J. MacQueen	OC 6/Gordon Highlanders	Commemorated on Loos Memorial to the Missing
Lt-Col. A. Parkin	OC 7/Northamptonshire	Commemorated on Loos Memorial to the Missing
Lt-Col. C. Radclyffe	OC 11/Essex	Commemorated on Loos Memorial to the Missing
T/Lt-Col. H. Collison-Morley	OC 1/19/Londons	Buried at Loos (Dud Corner) Cemetery
T/Lt-Col. A. Douglas-Hamilton	OC 6/Cameron Highlanders	Commemorated on Loos Memorial to the Missing
T/Lt-Col. A. Egerton	OC 1/Coldstream Guards	Buried at Vermelles Military Cemetery; killed by a shell in the Chalk Pit on 28 September
T/Lt-Col. F. Fairtlough	OC 8/Queens	Commemorated on Loos Memorial to the Missing
T/Lt-Col. W. Gaisford	OC 7/Seaforth Highlanders	Commemorated on Loos Memorial to the Missing
T/Lt-Col. M. Henderson	OC 9/Black Watch	Buried at Dud Corner Cemetery, Loos
T/Lt-Col. B. Leatham	OC 2/Wiltshire	Buried at Vermelles Military Cemetery
T/Lt-Col. B. Lefroy	OC 2/Royal Warwicks	Buried at Fouquieres Churchyard Cemetery Extension
T/Lt-Col. G. Neale	OC 3/Middlesex	Commemorated on Loos Memorial to the Missing; killed in attack on Fosse 8 28 september
T/Lt-Col. H. Madocks	OC 9/Royal Welch Fusiliers	Buried at Browns Road Cemetery, Festubert
T/Lt-Col. F. Radcliffe	OC 11/Essex	Commemorated on Loos Memorial to the Missing
T/Lt-Col. R. Richardson	OC 2/South Staffordshire	Commemorated on Loos Memorial to the Missing
T/Lt-Col. F. Romer	OC 8/Buffs	Commemorated on Loos Memorial to the Missing
T/Lt-Col. J. Stansfield	OC 2/Gordon Highlanders	Buried at Chocques Cemetery
T/Lt-Col. H. Walter	OC 8/Lincolns	Buried at Douai Communal Cemetery; died in enemy hands
T/Lt-Col. C. Worthington	OC 2/Buffs	Commemorated on Loos Memorial to the Missing; killed in attack on Fosse 8 28 september

Many of the men who died on or near the battlefield have no known grave today: most are commemorated on the Loos Memorial to the Missing, which surrounds Dud Corner Cemetery.