Passchendaele and the Tactical Learning Curve
A Third Battle at Ypres
After the slaughter of 1916, Field Marshal Sir Douglas Haig wanted a 1917 offensive that could break out of the Ypres salient, drive towards the Belgian coast, and capture the U-boat bases at Ostend and Zeebrugge. The result became known officially as the Third Battle of Ypres, but to the soldiers and the public as Passchendaele, after the small Flemish village finally captured in November.
The Third Battle of Ypres ran from 31 July to 10 November 1917. Haig aimed to break out of the salient, capture the Belgian coast and force a German collapse. After three months of mud and rain the Allies advanced about five miles for around 275,000 British and Empire casualties and roughly 220,000 German.
The Mud of Flanders
The opening preparation was the largest Allied bombardment yet seen — over four million shells fired in two weeks, nearly three times the number fired before the Somme. The bombardment shattered the drainage system that had kept the Flanders plain workable, and the wettest August in thirty years turned the broken ground into liquid mud. Tanks could not move. Wounded men drowned in shell holes. Each step forward had to be reclaimed metre by metre.
Three commanders led the British effort. General Sir Hubert Gough, an aggressive cavalry officer, was meant to break out fast; he could not. Haig replaced him with General Sir Herbert Plumer, a careful planner who had captured the Messines Ridge in June 1917 by detonating 19 huge mines under the German line — an explosion heard in London. Plumer’s methodical bite and hold approach — small advances secured by overwhelming artillery before the next move — produced the only consistent gains of the campaign at Menin Road, Polygon Wood and Broodseinde.
The Flanders plain was below sea level in places and only farmable because of three centuries of drainage ditches and pumps. The bombardment ground these to powder. Shell craters filled with rainwater within hours, then linked into chains of pools. Mud caked rifles, swallowed boots, and made shells that did not detonate vanish into the soft earth. Some historians argue Haig should have called off the offensive when the rain began — others note the strategic pressure to keep Germany occupied while the French army recovered from the mutinies that followed General Nivelle’s catastrophic April 1917 offensive.
The BEF’s Quiet Learning Curve
The image of static, futile slaughter has dominated public memory of the Western Front. Yet between 1915 and 1917 the British Expeditionary Force underwent a remarkable transformation. By Passchendaele the BEF was using tactics that simply did not exist on the Somme. Sound-ranging located German batteries from the noise of their own guns and silenced them before infantry attacked. Aerial photography produced detailed trench maps that artillery could fire on without giving away the attack by registering shots in advance.
Infantry tactics changed too. Battalions were reorganised into platoons combining riflemen, bombers, Lewis-gunners and rifle-grenadiers, so that small groups could fight forward against enemy strongpoints. The creeping barrage became more accurate, with shells lifting at a tighter walking pace. Tanks, although hopeless in the Flanders mud, proved their potential at Cambrai on 20 November 1917, when 476 tanks broke the Hindenburg Line on a six-mile front before German counter-attacks recovered most of the ground.
By the end of 1917 the BEF was deploying combined-arms tactics: predicted artillery fire, sound-ranging, aerial reconnaissance, platoon-level infantry organisation, mass tank attacks (Cambrai, 20 November) and a more accurate creeping barrage. The tools that would win the Hundred Days in 1918 were already in place.
Lions Led By Donkeys?
The verdict that brave British soldiers were ‘lions led by donkeys’ was popularised by Alan Clark’s 1961 book The Donkeys and reinforced by the 1989 BBC comedy Blackadder Goes Forth. Modern revisionist scholarship — led by historians such as Gary Sheffield, Peter Simkins and Dan Todman — has challenged this picture. They point to the BEF’s learning curve, to operational successes such as Messines and Cambrai, and to the war-winning advances of August–November 1918.
Critics highlight Haig’s persistence with attacks at Passchendaele after the rains broke and his apparent indifference to casualty figures. Defenders point to the strategic pressure to relieve French mutinies, the absence of any tactical alternative for breaking trench warfare in 1917, and the eventual victories he commanded in 1918. The most balanced verdict is that Haig was neither the cartoon donkey of Blackadder nor a flawless commander — he led an army through a learning process that, by 1918, had produced the most effective fighting force in the world.
Significance of 1917
Passchendaele did not break out to the coast. Yet by holding the salient and absorbing German divisions through autumn 1917, it kept the pressure on a Germany that was about to gain reinforcements from Russia’s collapse on the Eastern Front. Cambrai showed the world that mass tanks, surprise and combined arms could break the trench system. The hard infantry lessons of 1915–1917 produced an army that, despite the disaster of Passchendaele’s casualty list, would carry the Allies to victory the following year.