A General’s Redemption

On the morning of June 18, 1815, General Jean-Baptiste Drouet, Count d’Erlon, commander of the French I Corps, carried the weight of Napoleon’s disappointment. Two days earlier, his forces had marched fruitlessly between battlefields at Ligny and Quatre-Bras without engaging decisively, earning the Emperor’s fury. Now, as the mist cleared over the Belgian countryside, d’Erlon understood that only a successful breakthrough against Wellington’s lines could redeem his reputation. The target of his massive assault would be the eastern sector of the Allied position, which intelligence suggested was Wellington’s weaker flank. What followed would become one of the most debated tactical decisions in military history, a colossal infantry attack that might have changed Europe’s destiny had it succeeded.

The stage was set at Mont-Saint-Jean ridge, where the Duke of Wellington had positioned his Anglo-Allied army in a defensive masterpiece. The duke, anticipating Napoleon’s tactics, had strengthened his western flank near the Brussels road, leaving his eastern sector seemingly more vulnerable. This was the opportunity d’Erlon intended to exploit with four divisions totaling 18,000 infantrymen. The fate of France’s Hundred Days campaign rested on these formations breaking through what appeared to be undefended crestline.

The Illusion of Weakness

Wellington’s deployment appeared to present a perfect opportunity for d’Erlon. The British commander had indeed concentrated his strongest forces and artillery west of the Brussels road, making the eastern portion of his line seem comparatively weak. This was precisely the kind of tactical deception at which Wellington excelled. Having fought Napoleon’s marshals across the Iberian Peninsula for years, he understood French offensive doctrine intimately. The apparently weaker eastern flank was in fact a carefully designed killing ground.

The terrain itself told a story of defensive preparation. The forward slope featured Allied artillery batteries positioned to enfilade advancing troops. Beyond these guns, the crestline appeared deceptively empty, marked only by hedges lining a sunken lane. Captain von Rettburg of the King’s German Legion artillery recorded that portions of these hedges had been cut down to allow passage for guns and troops. What remained invisible to the French observers was the reverse slope, where the majority of Wellington’s infantry waited sheltered from artillery fire, lying or sitting to avoid roundshot that skimmed the ridge. This reverse slope defense would become Wellington’s trademark, and at Waterloo it would prove devastatingly effective.

The French Formation Puzzle

D’Erlon’s assault plan involved an unusual tactical formation that historians would debate for centuries. Rather than employing standard French attack columns, he ordered his divisions to form in an extraordinary hybrid formation. Each battalion would deploy in a standard three-rank line, but these battalion lines would then stack one behind another to create massive rectangular formations. General Marcognet’s 3rd Division, for instance, fielded eight battalions arrayed in 24 ranks, with each rank containing approximately 160 men.

This unconventional approach stemmed from d’Erlon’s experience fighting British infantry in the Peninsular War. He knew that standard French attack columns, while effective against many European armies, proved vulnerable to British linear formations. The two-rank British lines could deliver devastating volleys against the narrow fronts of French columns, whose rear ranks could not effectively return fire. D’Erlon’s solution attempted to combine the shock power of a column with the firepower of a line by creating formations that were essentially multiple battalion lines stacked deep.

The theory was that these enlarged formations would maintain sufficient frontage to engage British troops while retaining the moral cohesion and momentum of deep formations. Each division advanced with its skirmishers forward, who would theoretically weaken the British line before the main formation engaged. However, this complex maneuver required precise coordination across difficult terrain under enemy fire—a challenging proposition for even the most disciplined troops.

The Assault Unfolds

D’Erlon organized his corps to attack in echelon from east to west. General Quiot’s 1st Division led on the left near the Brussels road, targeting La Haye Sainte and the ridge beyond. They advanced with 800 cuirassiers—heavy cavalry—protecting their left flank. To Quiot’s right, the 2nd, 3rd, and 4th Divisions prepared to assault the eastern portion of the ridge, with part of their forces detached to attack the fortified Papelotte farm. The attack would thus engage Wellington’s entire eastern sector from La Haye Sainte to Papelotte.

As the drums began their relentless cadence, the four massive divisions descended into the valley separating the armies. The sight must have been awe-inspiring: nearly 18,000 men moving in coordinated formations across the muddy fields. Thirty-three French battalions advanced against seventeen Allied battalions—five Dutch, four Hanoverian, and eight veteran British units. While the numerical advantage appeared significant, the reality was more balanced due to differences in battalion sizes. French battalions averaged 550 men compared to 650 in British units, and four French battalions would be diverted to attacks on La Haye Sainte and Papelotte.

The initial advance proceeded with grim determination. French artillery attempted to soften the Allied position, but Wellington’s reverse slope defense minimized casualties. The attacking infantry could see little beyond the Allied guns on the forward slope and the hedges lining the sunken road. What they couldn’t see were the waiting infantrymen of Picton’s division, lying concealed on the reverse slope.

The British Response

As d’Erlon’s corps approached the Allied position, the true nature of Wellington’s defense revealed itself. The apparently weak eastern flank contained some of his most experienced troops. Sir Thomas Picton’s 5th Division, including veteran regiments that had fought across Spain, waited patiently on the reverse slope. These were not raw troops but battle-hardened professionals who understood the importance of discipline under fire.

Wellington’s artillery played a crucial role in the defense. As the French columns advanced, Allied guns switched from roundshot to canister—essentially giant shotguns that devastated packed formations at close range. The gradual slope allowed these guns to maintain visibility and fire until the last possible moment. Meanwhile, British skirmishers engaged their French counterparts in a deadly duel along the advance, thinning the ranks of French light infantry who were supposed to soften the defense.

The critical moment came as the French formations reached the sunken road and began ascending the final slope. The hedges, partially cut down as von Rettburg recorded, proved less obstacle than opportunity—they disrupted the French formations while providing some cover from Allied fire. But as the first ranks crested the ridge, they encountered not the broken and demoralized troops they expected, but disciplined volleys from Picton’s waiting infantry.

Tactical Disaster

The British response was characteristically methodical. As the French struggled to maintain formation crossing the sunken road and hedges, Picton’s men stood and delivered devastating volleys at close range. The deep French formations, intended to provide moral support, instead became killing zones where rear ranks pressed forward into the firestorm. The theoretical advantage of d’Erlon’s hybrid formation proved disastrous in practice—the stacked battalions could not effectively deploy their firepower while suffering the vulnerabilities of dense formations.

Then came the coup de grâce. As the French recoiled from the British volleys, the Earl of Uxbridge unleashed the British heavy cavalry. The Household and Union Brigades descended on the disorganized French formations, who had neither time nor space to form protective squares. In minutes, what had been a coordinated assault dissolved into chaos. Standards fell, formations broke, and thousands of veteran French infantry became a panicked mob fleeing down the slope they had so recently ascended with such confidence.

The cavalry pursuit went too far, eventually suffering crippling losses to French counter-charges, but the damage to d’Erlon’s corps was irreversible. In less than an hour, Napoleon’s best chance for victory had evaporated. The I Corps, intended as the hammer blow against Wellington’s line, would require hours to reorganize—time Napoleon didn’t have with Blücher’s Prussians approaching.

Historical Analysis

D’Erlon’s assault represents a fascinating case study in tactical evolution versus practical application. His hybrid formation attempted to address very real problems French commanders had experienced against British linear tactics in the Peninsula. The standard French attack column, so effective against other European armies, had repeatedly proven vulnerable to British fire discipline. D’Erlon’s innovation sought to create a formation with both sufficient frontage to engage in firefights and the psychological strength of deep formations.

Why then did it fail so catastrophically? The answer lies in the intersection of theory and reality. The formations were too complex to maintain under battle conditions, particularly crossing difficult terrain under artillery fire. The reverse slope defense neutralized French preparatory bombardment, and the sunken road disrupted cohesion at the critical moment. Most importantly, the British response—disciplined volleys followed by well-timed cavalry charges—exploited every weakness in the French plan.

Military historians have debated whether a more traditional attack formation might have succeeded. Standard French columns might have suffered less from British volleys by presenting narrower fronts, but would have been even more vulnerable to cavalry without time to form squares. The tragedy for d’Erlon is that his theoretical solution addressed real tactical problems but created new vulnerabilities that Wellington was perfectly positioned to exploit.

Legacy of the Assault

The failure of d’Erlon’s attack had consequences far beyond the afternoon of June 18. It forced Napoleon to commit his Imperial Guard earlier than planned in a desperate attempt to salvage the battle. It allowed Wellington to maintain his center-left, which would prove crucial in repelling the final French attacks. Most importantly, it bought precious time for Blücher’s Prussians to arrive and decide the outcome.

For military theorists, d’Erlon’s assault became a textbook example of how tactical innovations can fail when applied without sufficient consideration of terrain, enemy dispositions, and the friction of war. The French Army of 1815 struggled with integrating lessons from the Peninsula with Napoleonic doctrine, and d’Erlon’s formation represented an imperfect synthesis.

The attack also highlighted Wellington’s generalissimo. His careful deployment, use of terrain, and understanding of French tactical preferences created a perfect defensive trap. The apparently weak eastern flank was anything but, and d’Erlon’s corps advanced into a killing ground designed by a master of defensive warfare.

In the broader narrative of the Hundred Days, d’Erlon’s failed assault marked the beginning of the end for Napoleon. The Emperor had staked his return on decisive victory, and the shattering of his largest infantry corps in the battle’s first major attack undermined that possibility. The slope that promised redemption for d’Erlon instead became the pathway to Napoleon’s final exile and the end of an era.

Conclusion

The story of d’Erlon’s attack at Waterloo transcends its immediate tactical significance. It represents the collision of military evolution with the unchanging realities of combat: the importance of terrain, the value of discipline, and the unpredictability of battle. D’Erlon’s innovative formations, born from hard experience in Spain, might have succeeded under different circumstances against a different opponent. But against Wellington on the ridge of Mont-Saint-Jean, they proved fatally flawed.

The assault also reminds us of the human dimension of military history. D’Erlon, seeking to erase the memory of his June 16 failures, instead compounded them. Napoleon, watching his grand tactical design unravel in the smoke-filled valley, must have understood that his gamble was failing. And Wellington, observing from his command post, saw another demonstration of why his army had never been defeated by the French.

Two centuries later, the slope east of the Brussels road remains relatively unchanged. The sunken road has been largely filled in, but the gentle incline still reveals why Wellington chose his position and why d’Erlon’s men found it so unforgiving. The story of their attack endures as a powerful lesson in the complex relationship between military theory and the brutal reality of combat.