Breaking the Hindenburg Line, by Will Longstaff.
The first deliberate Allied step was the British Fourth Army’s attack at Amiens. Sir Henry Rawlinson wanted to attack to clear the Germans away from the key railway junction at that city, and detailed why it was tactically feasible as well as strategically desirable. His top two reasons were weak German defences and weak German defenders – a far cry from 1916 when the Allies attacked without much regard to the German situation. (The German defences were weak because they wanted to attack Amiens themselves, and thus had little incentive to dig elaborate defences; as long as they held the initiative there was little risk in weak defences, but when circumstances changed they did not react. Troop strengths were also reduced by the influenza epidemic.)
While Rawlinson wanted to attack, he was also cautious. He wanted all the tanks in the BEF, the best infantry (the Canadians and Australians), and strong artillery support, eventually totalling 60 train-loads of artillery. By 1918 the artillery units formed in 1916 and 1917 were in action, and there were finally enough guns to do all the tasks at one time, so destructive and neutralising fire could be one simultaneous deluge of shells. He also wanted surprise, which would keep the Germans weak, and would also have other tactical repercussions. For instance, surprise meant counter-battery fire would be far more effective: the Germans would not be moving their guns around to dodge increasing British fire, but would be stunned on Z-Day. Since the Germans would not be reinforcing their artillery, the British barrage guns could be further forwards and thus the creeping barrage could reach deeper into the German positions. (Without a preliminary counter-battery battle, more British guns were functional on Z-Day – 98. 5 per cent.) A bit of registration could be concealed through having newly arrived guns fire the routine `daily hate’ and harassment missions, but not all guns could be registered. Surprise was so important to Rawlinson that he gained approval for a BEF-wide deception plan, with a series of rumours, and also made sure every man in the Fourth Army received a leaflet headed KEEP YOUR MOUTH SHUT. Revealing the build-up would put so much at risk that he decided the reinforcing guns would only fire if there were a major German attack – a simple probe or raid would not trigger massive defensive firepower – and the decision about what to fire was decentralised to the CBSOs, presumably because they would have plenty of information and they controlled much of the heavy artillery. It was a remarkable display of how the BEF could be at once centralised and decentralised.
The battle began at 04. 20 hrs on 8 August. Surprise was total, and most of the artillery elements worked like clockwork; even when mist meant the infantry could not see the barrage, they could hear it and follow it. Twothirds of the heavy guns were firing counter-battery missions, and 95 per cent of the German artillery had been correctly located. Many batteries were abandoned without firing (some still had their muzzle-caps fitted) since German artillerists’ morale was no higher than their infantry’s. (The Germans had been reorganising their artillery, and were now mixing a bit of heavy artillery with the field artillery as `close-range groups’ to support the infantry regiments, while a `long-range group’ of heavy artillery was responsible for other missions. It hardly mattered on the first day at Amiens, but they were trying out new methods.) Other batteries were found demolished with their horses dead and the gunners fled once there was no point in trying to continue the fight. The Canadians had somewhat poorer artillery support since they had been the last to arrive and were not permitted to fire any preliminary rounds; it did not help them much that the French First Army (on their right) was also attacking but at H+40. The French had no tanks and needed a short bombardment, but for the first few minutes the Canadian flank was only supported by fire instead of by advancing troops. The Canadians did something unusual for counter-battery fire: instead of one battery firing on a German battery, they assigned one gun from three or four different batteries to each German battery. They knew their accuracy would not be perfect, but by blending in several guns with different errors, on average the targets would be hit. It worked, and they continued the technique through to the end of the war – despite the extra paperwork involved.
The creeping barrage was fired as far as the field artillery could reach, and then the barrage was held on that line until H+240 as a protective barrage for the infantry to mop up and reserves to start moving. The barrage then stopped, and the infantry/cavalry/tank forces could fight their own way forwards. Some field artillery did advance (about a brigade per infantry division, and it advanced when ordered to by the supported infantry) and there were thorough plans to open lanes in the wire and have signallers to connect the guns to the infantry, but these guns fired concentrations where Germans were resisting rather than a barrage. While the problems of cavalry-tank coordination are better known, it was equally hard to coordinate guns (even the Royal Horse Artillery) and cavalry because mobility was so different. The RAF provided valuable support to both infantry and artillery. Many zone calls provided information and targeting, and there was some strafing of German artillery where it was beyond the range of counter-battery guns. Smoke barrages had formed part of the original plan (not just providing some cover to the advancing infantry but blinding specific German observation posts) and in later phases, when smoke was needed beyond artillery range, the RAF tried dropping large quantities of smoke bombs.
The results on 8 August were excellent: up to 8 kilometres gained across the 24-kilometre front, about 18, 000 prisoners (plus probably 10, 000 killed and wounded who retreated) and around 400 guns. In yet another way surprise paid off: the Royal Artillery suffered no casualties from German shelling. When the attack continued on 9 August, progress slowed markedly. The Germans flung in more reserves than the BEF had anticipated, and the Allied forces were fatigued and had suffered casualties. They were also far less organised (16 British brigades would attack on 9 August, but they had 13 different start times as coordination broke down; individual attacks also had far less artillery support), and it was harder to move supplies forwards and get information back. All these were familiar problems in the Great War, indeed in warfare in general. Still, the Allies had the advantage and fought their way forwards, gaining ground and taking prisoners. (The artillery had its sound-ranging specialists and observers moving forwards on the 9th to support the fight when the RAF could not.) But on the 10th Rawlinson was already suggesting to Haig that his attack be wound down and the attack widened to the flanks, with the British Third Army on the left and the French First Army on the right.
Rawlinson’s attack was continued for a few more days, partly to wring maximum effect from the initial success but partly to cover the pre-preparations of Sir Julian Byng’s Third Army. (The attack would ultimately take over 25, 000 prisoners, inflict roughly 50, 000 more casualties on the Germans, take 600 guns, and take up to 19 kilometres of ground.) Intangibly, Amiens was proof of the momentum swing on the Western Front and in the whole war. The Germans were not to attack again, but the Allies would continue to rain down blows throughout the `Hundred Days’ until the German army was defeated. When Ludendorff referred to 8 August as a `Black Day’ for the Germans, he was not just referring to the casualties (although they were heavy, and the large number of prisoners showed how fragile German morale was); he had been shown that he was no longer calling the shots. The Allies were, and Foch’s plans for successive attacks would continue along the front.
Byng had been making phony attack preparations as part of the deception plan, and now the BEF could make Third Army’s phony preparations real while the Fourth Army’s real attack (which was becoming more cautious) became the deception. Byng had few tanks, which made protecting them from German artillery even more important, so the Third Army stressed its counter-battery efforts. This included integrating the RAF and artillery; aircraft were earmarked to hunt for German anti-tank guns and not only strafe them but call in the 60-pounder batteries which were on call – their sole mission was to hit anti-tank guns. At first Byng just cleared the German outpost zone, although in places the German artillery resisted stoutly and delayed the British; he then paused and brought up his guns and prepared (while beating off German counter-attacks) for the main attack. After only a day of preparations (and the Germans weakening them-selves through ineffective counter-attacks), he was ready and cracked the German main line with only modest resources. Even in the V Corps’ sector, where the German artillery had caused problems on 21 August, the attack on 23 August gained ground readily. The results (up to 4 miles of ground, over 10, 000 prisoners plus other casualties) were far less dramatic than in the surprise attack at Amiens, but they showed both sides that the Germans could be driven out of their positions by an `ordinary’ attack – tanks were not necessarily the key to an attack, nor were Dominion `shock troops’.
German reserve divisions were getting little time to rest before having to go back into battle. On the 23rd Herbert Sulzbach heard the battle over the horizon. His reserve positions in a pretty village were `invaded by the rumbling and rolling of the new large-scale battle between Noyon and Laon; it seems to be the fourth phase of the Foch offensive, directed against our Fourth Army’.
Ludendorff recognised the weakness of his position and tried to pull back to a `winter’ line in front of the Hindenburg Line where he could reorganise. But he needed time to actually build the winter line and time to rest his troops and restore morale. He tried to buy time with rearguards, and both sides had to coordinate semi-mobile operations. There were few or no trenches, so it was not trench warfare, but there was a reasonable front line so it was not quite the mobile operations that had been taught before the war. The Germans found it hard to meld artillery into the rearguards for a range of reasons, not least because the gunners might simply not know where the infantry was, as units were moving every day or two. Meanwhile, the Germans had identified tanks as a key Allied weapon, not just for their firepower and mobility but because they demoralised the German infantry. New guidelines and methods came down from on high that looked rather like the British methods of the late spring of 1918: guns to be mobile, distributed in depth, withdraw if losing the battle, counter-battery fire in lulls in the overall fighting, counter-preparation fire instead of defensive barrages, and the like. The anti-tank instructions were unrealistic: it was all very well to say that the field artillery needed to be even more mobile and move to support the infantry, but where were the horses to come from? Supplies might be a problem too, as resupply points changed erratically. But morale seems to have been the worst issue, as infantry frequently simply pulled back past batteries, or batteries fired off the ammunition they had (at whatever target they selected) and then pulled back themselves. At the end of August the British broke Ludendorff’s planned winter line in two places, the Canadians breaking through the heavy fortifications of the Drocourt-Queant Line (an extension of the Hindenburg Line) while the Australians fought their way up Mont St Quentin.
These actions set off another round of German withdrawals, this time back to the Hindenburg Line itself. For the BEF much of September would consist of day after day of semi-mobile operations, and they became fairly adept at it. Infantry divisions were typically rotated every two or three days to rest and reorganise, but because the artillery did not rotate as frequently, so there were 4 to 6 brigades of field artillery available to support each infantry division, and also a brigade of heavy artillery. 43 No more than one-third would be moving at once, so plenty of fire support was available. These brigades may have been available, but they were not necessarily engaged; ammunition supplies were problematic, and if the Germans were not entrenched there was no need to fire much of a barrage. There was seldom a bombardment, just a creeping barrage in the morning to help the infantry get started and suppress whatever defences the Germans had organised overnight. When ammunition was short, the creeping barrage might do little more than guide the infantry forwards, and the few smoke (and incendiary) shells mixed in were very useful because they stood out. Some days the infantry did not even know where they were, and the barrage would start firing along a terrain feature (such as a road) and the infantry would advance to the start line before the barrage even began moving. German strong-points would receive concentrated fire, and there might also be enough of a bombardment plan to shell suspected strong-points ahead of the barrage. Much fire was observed rather than planned from the map; that this was a novelty shows how much things had changed since 1914. Against lighter defences the concentrated heavy artillery was enormously potent: `Sections of trench were flattened out in minutes, dugouts blown in, walls collapsed, machine guns and mortars were covered by earth and rubbish, and ammunition dumps exploded.’ Artillery support did not stop with the barrage; typically a field battery moved forwards with each infantry brigade headquarters to provide on-call indirect fire, while the leading battalions could have a section (two guns) pushed forwards to blast machine-gun nests. A number of 6-inch mortars were also pushed forwards on wagons, with improvised mounts on the wagon bed so the mortar did not have to be dismounted.
