On July 15, 1918 the German army launched its fifth major offensive on the Western Front since 21 March. The first two had been directed against the British, on the old Somme battlefields and then in Flanders. Each had followed the line of least resistance, making dramatic progress where the line was weakest but losing strategic coherence in the process.

The French commander-in-chief, Philippe Petain, rushed reserves to support the British, but was worried about exposing his own sector of the line to the German onslaught. His fears proved well founded. On May 27, the Germans directed their third attack against a quiet sector of the French line at the Chemin des Dames. The German First Quartermaster General, Erich Ludendorff, had intended this operation to halt the French support of the British but its success brought his heavy artillery within range of Paris. Panic gripped the French capital and what had been a diversion became a main effort. The fourth attack, in June, was designed to broaden this advantage but it was the fifth, pushed across the river Marne, where in early September 1914 the allies had checked the German invasion at the outbreak of the war, that sought to exploit the salient created on May 27.

The French knew it was coming. They thinned out their front line, putting their main strength out of reach of the German artillery bombardment. The Germans made initial gains, but as they did so they advanced into a sack. On July 18, Ferdinand Foch, who was confirmed as the allied commander-in-chief in April, ordered a counter-attack. The French plan was to strike the German flanks from west and east, so trapping the Germans in a pocket south of the Marne

“Foch has scored”, wrote John Charteris, formerly Douglas Haig’s Director of Military Intelligence and a future MP for Dumfriesshire. Foch had tested the patience of both Haig and Petain between April and June. Each had wanted to prioritise his own army and to take the opportunity provided by the German offensives, and the salients that they had formed, to launch local counter-attacks. Foch realised that such an approach had been the allies’ undoing in the past.

The Germans had sufficient reserves to handle them, and the allies would dissipate their forces just as the Germans had done. Between March 21and July 15 they had nearly one million men killed, wounded and captured and they had been drawn forward from the well prepared Siegfried Stellung (or Hindenburg Line), to which they had deliberately withdrawn in spring 1917, and so held an extended front with fewer men.

Ostensibly the allies had appointed Foch as their generalissimo to surmount an immediate crisis. In reality it had become a strategic necessity, less because of Anglo-French tensions than because of the arrival of the American Expeditionary Force in 1918. By the summer of 1919, it would muster four million men, and would be as big as the British and French armies combined.

The allies could therefore plan on winning the war by late 1919 or, at the latest, in 1920. However, the United States president, Woodrow Wilson, was determined to keep the American Expeditionary Force independent, just as he insisted that the US was an associate power and not a full ally. Foch’s appointment was therefore also designed to square off the Americans’ independence while ensuring strategic coherence. Each of the national commanders, Haig, Petain and John J Pershing, retained operational authority and had the right of appeal to his own government.

HeraldScotland:

It was a sign of Foch’s success as an allied supremo that none of them exercised that authority. Foch’s responsibility was for strategy. The military representatives of the Supreme War Council, a body created in late 1917 to coordinate the allies but now largely redundant, were refashioned to plan the arrival of the Americans, to phase their entry into the battle and to coordinate the Western Front with the other principal fronts, in Italy, the Balkans and Palestine.

In previous years, the eastern fronts had been comparable in importance with the Western Front, tying down not just a large proportion of the German army but also their allies, the Austro-Hungarians, the Bulgarians and the Ottomans. But in November 1917 the Bolshevik revolution had taken the Russians out of the war, and so the Western Front had become the principal front for the Germans as it was for the French and British.

The shipping required to supply industrialised warfare precluded Britain deploying a mass army anywhere else, and exactly the same consideration applied to the Americans. By early 1918, thanks not least to the Americans’ contribution at sea, the allies had overcome the challenge of the German U-boats to their control of the Atlantic and so could deliver the Doughboys to Le Havre and Brest.

On July 18 the Americans supported the French counter-attack on the Marne at Chateau Thierry. Both sides realised that the tide was now turning, for all that the bulk of the German troops managed to escape from the pocket south of the river. German morale, buoyed by the prospect of finally getting to Paris, was dashed. For the French, the arrival of the Americans, seemingly bronzed, fit and enthusiastic, offered the hope of eventual victory.

Foch, flushed with his success on the Marne, convened a meeting of his allied commanders at his headquarters at Bombon on July 24 and told them the time had come to attack. He proposed successive operations, conducted with only short intervening breaks, along the length of the Western Front. Each attack should aim at surprise, an advantage forfeited by the long preliminary bombardments of earlier offensives, and should be delivered with overwhelming force. By 1918 the allies on the Western Front could bring their material superiority to bear on the battlefield: short bombardments could be as destructive as long, as they now had more guns and those guns could achieve greater accuracy, and they could mount attacks without moving large quantities of munitions from one sector to another, a process which both induced delay and forfeited surprise.

Foch proposed that each of these offensives should aim at “useful results”: the clearing of the Picardy plateau, so freeing the danger to Amiens and the northern railway network; the recovery of the industrial resources of northern France; the continuation of the attack in Champagne, to free up the Paris-Nancy railway; and the elimination of the St Mihiel salient south of Verdun. The focus on clearing the main railway lines was designed to ensure that subsequent operations could be maintained without pause. Foch was now linking tactical methods to strategic objectives by way of an operational design, and using all arms in combination to do so.

Foch liked to imply that on July 24 he had been heard in stunned silence: “They all took me for a fool”, he told one of his biographers. The allied armies were exhausted, battered by five successive German offensives in four months. In practice all three national commanders accepted the plan within 48 hours. Haig was the first beneficiary. Foch gave him command of the French 1st Army for an attack at Amiens, to be conducted in conjunction with the British 4th Army on August 8. Haig’s success vindicated Foch’s urgency, and the battle became the first of a sequence which continued for 100 days.

At the end of September the British broke the Hindenburg Line, and at the other end of the front the Americans launched their first major independent offensive in the Meuse-Argonne, which continued till the war’s end. Both Foch and Haig had been accused of a readiness to push on with offensives which they ought to have closed down. Now they were the right men in the right place, ready to exploit the opportunities which presented themselves with a speed that surprised Haig. Although Foch began to realise that victory was possible before the end of the year, the politicians did not.They had learned through bitter experience not to trust the generals’ optimism. They were therefore surprised when, on October 1, Ludendorff called for an immediate armistice.

Nor were they alone. The newly appointed German chancellor, Max von Baden, recognised that Germany must seek to end the war but expected an orderly negotiation. Although Ludendorff later called the Battle of Amiens “the black day of the German army”, he had rejected the call of the Austro-Hungarian chief of staff for an immediate peace five days later. Even after the rupture of the Hindenburg Liner, many in the supreme command continued to see the situation in the west as manageable, and were stunned on September 30 when Ludendorff told them that he proposed to demand an immediate armistice.

Sir Hew Strachan is Professor of International Relations at the University of St Andrews and a member of the WW100 Scotland Panel.

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