The Allies had two British and one French infantry divisions with fairly limited support outside divisional resources. Five brigades of heavy artillery, one of field artillery, an extra infantry brigade, a company of Mk 1 tanks and a brigade of cavalry in Corps reserves. Both British Divisions had one mile frontages and the bulk of the support assets, whereas the French had a rather sticky wicket with a one and half mile frontage but only one extra groupe each of 75s and 155s. They also had a strongly fortifed redoubt on their front. In the foreground above you can see General Gows newly arrived division with its company of tanks, formed up two brigades up, two back. Beyond that is General Ellsemores experienced division formed up tow up one back with the Corps cavalry deep in the rear. In the far distance is General Armatys French division, three up one back and with distinctly thin artillery support (one gun per 24 yards, the British had one gun per 13 yards). Much of the Allied air arm was grounded by bad weather, and the British have cruelly grabbed all the available spotter planes.
The German defences look rather thin, but are typical for 1916. Two wired trench systems a few kilometres apart with the front line strongly held. Each regimental sector (approx one mile) is held with two infantry battalions and the regimental machineguns in concreted emplacements in the front line, suported by the regimental mortar detachment (36 minenwerfers and granatenwerfers) from entrenchments to the rear and the second line thinly held by one infantry battalion. The immediate tactical reserves are the regimental stormtroop companies, but amply warned by the week long bombardment, in operational reserve are three eingrif regiments ready to counterattack and regain any lost ground 'at all costs' (as the manual says). This brings the defenders close to the recommended strength of one division per 5km supported by another in reserve. Defensive artillery density is one gun per 26 yards, quite sufficient to lay down a devastating SOS barrage in nomansland unless suppressed. 
The British offensive opened with a week long barrage. This utterly devastated the German second line, and also succeeded in smashing up the infantry, mortars and pillboxes in the front line although not decisively. Wire cutting was patchy, in some areas it was cleared altgother, but in most sectors it was partially cut. Importantly for the French, the dense wire in front of the enemy redoubt facing them was at least reduced. The ground was heavily cratered throughout the depth of the defences, which didn't please the tank commanders.
In the picture (view north to south) the first wave rolls across Nomansland covered by the creeping barrage as Germans lay down their own defensive SOS barrage. In this case, fog greatly aided the attack. In the south the French chose to delay the assault until they had thoroughly suppressed the defenders, but in the north the British attacked. General Ellsmores troops lay out in Nomansland and by and large managed to surprise the German defenders, as did General Gows men although with further to move they suffered heavily from the barrage and their tanks lagged behind the infantry in the cratered ground, also losing vehicles to the intense defensive barrage.
After a pause for regrouping, the British pressed on in the south behind the barrage. In some sectors the troops began to straggle quite badly, hampered by the mud. In the south the French assault had limited success, although they managed to break thruogh in the centre, the German defences on each side held and the French infantry were massacred in nomansland. In the picture Generla Gows right wing and General Ellsmores left wing have managed to take the German communications zone against patchy resistance while the rest of their troops are stuck trench clearing or straggling up in the mud. In the far distance the big blue mass is the French preparing to press on in their centre.
Initially the German reaction was limited to local counterattacks by the stormtroop companies, but as they day wore on, the Eingrif regiments began to arrive. The British were quite content to push up to the German second line and hang on to their gains covered by the barrage. There was some talk about trying to push into the devastated German second line, but this came to nothing. In the final positions above both British divisions have consolidated in front of the German second line and in the far south a lonely French infantry battalion has also pushed forward, but its flanks are hanging in the air and it will have to withdraw at nightfall. One German regiment is massing in the centre, but faced with the British barrage, its attack is likely to fail. Astonishingly there are still some tanks left in action at this late stage. The German artillery position is also looking quite ragged, counterbattery fire during the bombardment and in direct support of the attack having taken its toll, and the Allied fighters have swept the German airforce from the sky.
In the end, quite a succesful operation for a limited attack. Allied losses were quite steep, particularly as they pushed their massed infantry brigades right through the unsuppressed German artillery, some 16 battalions being rendered ineffective (out of the 36 they started with). The Germans also suffered heavily as they lost almost all their infantry and most of their heavy weapons, in the line holding division at any rate, the Eingrif division never really got into action. Historically that was the major problem with this form of defence. It formed a very tough crust for the Allies to pierce, but by massing their forces forward in the trench system, they presented an excellent static artillery target and by the end of 1916 the Germans decided the losses suffered were unsustainable and adopted new methods.
On to spring 1917 next, when the Allies will fin dout waht the new system of defence entails!
