8 inches (204 mm) heavy guns in battery on the Somme in 1916.
10.5cm leFH16 howitzer.
21cm / 24cm Paris-Geschutz (Paris Gun) – Long-Range Super Heavy Railway Gun.
Map showing rolling artillery barrage for advance at Vimy Ridge 1917.
The ‘fire’ component of the Allies’ advantage in fire and movement came primarily from more traditional artillery technology, though much enhanced by wartime refinements. The German artillery revolution associated with Bruchmüller and Pulkowsky had its Allied counterpart, perhaps less trumpeted but no less effective. Its preconditions were transformations in gun and shell production, and in logistics. In the final weeks Allied gunners were struck by how their opponents’ professionalism was deteriorating, whereas by this stage France and Britain could sustain vastly higher levels of munitions consumption than four years previously, repair and replace their cannon and howitzers, and make good from stocks their losses during Ludendorff’s offensives, while all the time equipping other armies besides their own. The origins of these changes reached back into the nineteenth century, when steel breech-loading cannon with rifled barrels had replaced iron or bronze smoothbore muzzle loaders, and smokeless high explosive had replaced brown powder as the propellant for the shell and as the charge inside it. The French 75 mm quick-firing field gun, developed in the 1890s, was fitted with a hydraulic piston that absorbed the recoil from the barrel, thus enabling it to be fired repeatedly without being relayed, delivering up to twenty rounds per minute instead of the previous four. Other armies imitated it, introducing the 77 mm gun in Germany and the 18-pounder in Britain, and quick-firing spread to heavier calibres. Moreover, whereas in the American Civil War ranges of 1,000 yards were typical, by 1914 the British artillery could already fire at 5,000–10,000.
After the fighting got bogged down and the belligerents ran into ‘shell shortages’, the manufacturing and logistical revolutions got under way. In the French army, the artillery almost tripled in personnel during the war, rising from 18 per cent to 36 per cent of total effectives. By 1918 two thirds of its guns were new or refurbished and one third of the field artillery was motor-drawn rather than horse-drawn. Whereas the number of field guns was similar to that in 1914, that of heavy guns had risen from 300 to nearly 5,000. Similarly, in 1914 the BEF had only twenty-four guns firing shells of over 60 pounds (powerful enough to suppress enemy batteries), but by 1918 it had 2,000 medium and heavy howitzers, and for the first time possessed enough heavy artillery to launch major assaults at more than one point without redeploying the rest of the army’s heavy guns to the attack sector. In both armies expansion went alongside centralization. In the British army, the average number of guns available to support each infantry division rose from 68 to 100 in 1914–18, but the numbers actually controlled by a division fell from 76 to 48, the vastly increased number of larger-calibre weapons being assigned to corps and army commands. The French heavier calibres, similarly, were assigned in spring 1918 to a Réserve générale de l’artillerie – partly tractor-drawn – that could be shuttled rapidly around the front. Not only was there a huge increase in curved-trajectory weapons (howitzers and mortars), which were easier to fire from concealed positions and of greater value against earthworks, but shell charges shifted from shrapnel towards high explosive. The British 106 fuse, employed from 1917, detonated shells on impact with the ground rather than after being buried in it, so that they spread blast horizontally and better destroyed barbed wire. Indeed, some commentators felt the change had gone too far, and in the more mobile 1918 campaigning lighter calibres and shrapnel shells (of which the French army now found it had a shortage) again became relevant.
Not only had the artillery’s equipment been transformed, but also its tactics. Operating at much greater ranges against infantry concealed in trenches and enemy guns behind reverse slopes obliged the gunners to practise indirect rather than direct fire. Initially this meant guidance by forward observation officers – a notably hazardous occupation – who indicated whether ranging shots were falling short of or beyond the target. As the war progressed the task passed increasingly to balloons and aircraft, whose crews by 1917 could communicate with the ground by wireless in Morse code, although they could not receive radio messages in return. Such work was slow and arduous, and impeded by poor wireless reception, German fighters, and the youth and inexperience of many aircrews. The most radical form of indirect fire was ‘predicted shooting’, i.e. firing at a map co-ordinate, which could be done without ranging shots. Its preconditions were precise knowledge of the target’s co-ordinates and an accurate map of the combat zone, but another feature of the war was a revolution in cartography. When the British arrived on the Western Front their maps were wholly inadequate, but by 1917 their Third Army headquarters was issuing 1:10,000 plans of the two sides’ trench systems that were updated daily. Between 1914 and 1918 the British army’s surveyors prepared and distributed some 32 million maps and their French counterparts 30 million: the Germans even more.
Maps were of little use unless prospective targets could be pinpointed. Aerial photography was the key to this development: by 1917, 90 per cent of British counter-battery observation was by aircraft linked to wireless. Flash-spotting – tracing a gun by the flash from its muzzle – became less useful after the Germans started using flashless powders in 1917,206 but sound-ranging remained invaluable. The necessary equipment (the Bull-Tucker set) was French in origin but perfected by the British in 1916, and the Americans put it into mass production. It used trigonometry and an array of microphones to locate a gun from the sound of the report when it fired. By 1918 several guns could be detected simultaneously, within minutes of their first shot. The Germans had a much cruder system, relying on individuals with stopwatches, and stood at a major disadvantage. Moreover, from 1917 every BEF corps headquarters established a counter-battery staff office (CBSO), which centralized intelligence and reported daily and weekly on the location of the enemy guns and drew up fire plans against them. Before ‘Michael’ the system worked poorly, owing to the silence of the German guns and Allied aircraft failing to spot them; but it lay behind the successes at Hamel and on 8 August, and the Germans, once again, lacked anything comparable. By the eve of the Battle of Amiens the British had located 504 out of 530 German guns in the attack sector; and they had four heavy guns (with ample ammunition) to train on each battery. The suppression of the German artillery resulted from painstaking work beforehand, to be repeated in later attacks.
The two obstacles halting Allied infantry in the middle years of the war were artillery and machine guns. If counter-battery fire addressed the first of these, the second were the target of the creeping barrage, which Bruchmüller may have copied from his enemies. The British experimented with it at Loos in 1915, and adopted it more generally during the Somme, from which time the French imitated them. The basic principle was for the assaulting infantry to follow as closely as possible behind an advancing bombardment, the casualties that might result from ‘friendly fire’ being lower than if the troops hung back until the defenders emerged from cover. By 1918 the creeping barrage was well-established practice, although debate continued about the most appropriate speed and mix of munitions. In the British barrages of the ‘Hundred Days’ between August and November, shrapnel was normally the largest element, but supplemented by high explosive, and by smoke shells to impede visibility. It had become easier to regulate them as the British and French armies had each developed wireless communication, and both were much better equipped with radio as well as telephone links than were the Germans. A creeping barrage was no longer a single curtain of fire but several, designed to isolate the enemy front line and fend off counter-attacks, and Canadian practice – unlike German – was to go to the limit of the barrage but not beyond it. German army assessments attributed the British victories of August and September not to the infantry but the superiority of the artillery, the creeping barrage, and the curtain of fire that impeded reinforcement.
Creeping barrages were symptomatic of a change in doctrine, which mirrored developments on the German side. German guidelines also stressed counter-battery fire and the Feuerwalze, and that the artillery’s objective was less ‘complete annihilation and destruction, than shattering the enemy’s morale’. On the Allied side, the British attack at Messines ridge in June 1917 and the French one at La Malmaison in October, both successful operations by Western Front standards, had represented the acme of positional warfare. Pétain’s 31 October 1917 general instruction, issued after the latter, still envisaged that the artillery should destroy the enemy’s positions prior to the infantry advance. But in contrast his Directive No. 5 of 12 July 1918 stressed the opportunity for surprise against what were now much weaker German defences. The French artillery had grown adept at indirect fire without registration and could lay down smaller, shorter bombardments of only a few hours, even at night or in bad weather. Guns pulled by tractors could arrive rapidly, and using lighter 75 mm and 105 mm pieces enabled lorries to carry more shells. The BEF too altered its objective from destruction towards ‘neutralization’, abandoning as unrealistic the goal of obliterating the enemy defences, although this trend applied only up to a point. At Cambrai in November 1917 the Third Army dispensed with registration altogether, the bombardment coinciding with the infantry and tank attack. On 8 August 1918 the bombardment started at 4.20 and the attack at 4.24 a.m. Even so the British did not rely purely on surprise and hurricane bombardments, and before the attack on the Hindenburg Line – when they knew they could not conceal their intentions – the weight of munitions was formidable. By now the BEF could calculate the scale of bombardment needed, and its estimates were vindicated, as its 106 fuses cut the wire, its counter-battery fire (using twice the weight of heavy shell as on 8 August) was much more accurate than two years previously and included mustard gas, and it was no longer true as in 1916 that 30 per cent of the rounds fired were duds. In short, the Allies combined neutralization of improvised positions with efficient destruction of established ones, both driving back the Germans in open country and dislodging them when they chose to make a stand. And although the American bombardments on the Meuse–Argonne were to begin with much less successful, during October 1918 the AEF too – at least at divisional level – adopted similar methods