Like a well-constructed tragedy, the campaign unfolded in five acts with Prologue and Epilogue.

Prologue: The French forces began converging on the border with Belgium, and the border was sealed. On the 12th, Napoleon left Paris and moved to his Army’s Center of Operations at Avesnes.

Act One: The French march of concentration:

On June 15th, the French Army was unleashed across the Sambre River. At their first encounter, Allied screening forces sent out the warning to their respective Headquarters, and fell back toward their advancing compatriots.

Act Two: Allied reaction and French Advance:

The Allies executed a forward concentration behind the cover of their respective screens. As the 16th dawned, troops of both sides still converged on the battlefields of Ligny and Quatre Bras. The French had marched 16 miles since the previous morning.

Act Three: The Battles of Quatre Bras and Ligny:

The French attacked on two fronts simultaneously. The tenacious defense of Quatre Bras by the Anglo-Allied troops saved the Prussians from receiving the full weight of the Armée du Nord. Napoleon’s hoped-for knock-out blow remained undelivered. The Campaign would continue.

Act Four: The Allied retreat and French pursuit:

The Allies withdrew in tandem, on parallel routes north, and Napoleon separated the two wings of his army, ordering Marshal Grouchy on the track on the Prussians while he pursued Wellington. Grouchy’s prescribed route, through Gembloux, was wide of the mark, and took him to the outer flank, allowing the Prussians to interpose themselves between the two French wings.

Act Five: The Battle of Waterloo:

While Grouchy engaged the Prussian rear-guard at Wavre, Wellington fought a successful defensive battle at Waterloo, managing to cling to his ridge until the arrival of Blücher.

Epilogue: The French retreated—the routed forces of Napoleon back toward Charleroi; the intact wing of Grouchy in a south-easterly direction, toward Namur.

Napoleon ordered a general concentration of the army around Beaumont on June 9th. The initial concentration area given to the left wing—I and II Corps—was west of Charleroi, at Valenciennes and Avenes, about 44 and 34 miles west of Charleroi, respectively. This concentration was designed to portend an attack near Mons, threatening Wellington’s communications, which ran toward the North Sea coast at Ostend. On the right wing, III Corps moved up to Rocroi, 40 miles south of Charleroi, and IV Corps approached from Metz. The cavalry and VI Corps bivouacked in the center, while Rapp’s V Corps remained on the Rhine to face the oncoming Austrians.

Napoleon with his Imperial Guard remained in Paris as long as possible, finally departing Paris en route to the army at 03.30 on June 12, 1815. His departure would announce to the whole world the commencement of the campaign. Passing through Soissons, depot for the Armée du Nord, the Emperor arrived in Laon, another important stage on the line of communications, at Noon the same day. He spent the 13th at Avesnes, the Army’s Center of Operations, looking to the administrative arrangements for his army’s supply.

Napoleon arrived with the Guard at Beaumont on the 14th, the concentration point of his army. The formation adopted by Napoleon for this campaign comprised two wings and a reserve—the left, under Ney, with two corps and the Guard light cavalry; the right, under Grouchy, also with two corps and an extra division of cavalry; and the reserve, comprising the Guard, the Cavalry Reserve, and the understrength VI Corps. In comparison to the formation of prior years, this one lacked a critical element, namely, an advanced guard of two corps at the point.