The Grande Armée, consisting of as many as 650,000 men (roughly half of whom were French, with the remainder coming from allies or subject areas), crossed the Neman river on 24 June 1812.

On 9 January 1812, French troops suddenly occupied Swedish Pomerania, ostensibly to end the illegal trade with the United Kingdom from Sweden, which was in violation of the Continental System.

[4] After the French Grande Armée retreated from Moscow on 18/19 October 1812 and suffered heavy casualties due to extreme cold, food shortages and repeated Russian attacks, Napoleon did not seem to be as invincible as before.

On 14 December, the last French troops had left Russian soil, and Paris' allies were seriously considering rebellion and joining the Tsar's side.

He had to judge whether the moment was favorable for starting a war of liberation; and, whatever might be the enthusiasm of his junior staff-officers, Yorck had no illusions as to the safety of his own head, and negotiated with Clausewitz.

The news was received with the wildest enthusiasm in Prussia, but the Prussian Court dared not yet throw off the mask, and an order was despatched suspending Yorck from his command pending a court-martial.

Diebitsch refused to let the bearer pass through his lines, and the general was finally absolved when the Treaty of Kalisch (28 February 1813) definitely ranged Prussia on the side of the Allies.

Meanwhile, Napoleon withdrew some 20,000 troops from the ongoing Peninsular War to reinforce his position in Central Europe, which left his Iberian forces weakened and vulnerable to Anglo–Spanish–Portuguese attacks.

Wellington led a 123,000-strong army across northern Spain, taking Burgos in late May, and decisively defeating Jourdan at the Battle of Vitoria on 21 June.

Frederick William of Prussia had always viewed a renewed war with France as dubious, and the two defeats at Lützen and Bautzen had led him to reconsider peace.

[11] The belligerents declared an armistice from 4 June 1813 which lasted until 13 August, during which time both sides attempted to recover from approximately a quarter of a million losses since April.

During the armistice, three Allied sovereigns, Alexander of Russia, Frederick William of Prussia, and Carl Johan of Sweden (by then Regent of the kingdom due to his adoptive father's illness) met at Trachenberg Castle in Silesia to coordinate the war effort.

Allied staffs began creating a plan for the campaign wherein Bernadotte once again put to use his fifteen years of experience as a French general as well as his familiarity with Napoleon.

[15] Following the end of the armistice, Napoleon seemed to have regained the initiative at Dresden (26–27 August 1813), where he inflicted one of the most lop-sided losses of the era on the Prussian-Russian-Austrian forces.

Napoleon turned the Allied Left Flank, and in skilful use of terrain, pinned it against the flooded Weißeritz river and isolated it from the rest of the Coalition Army.

Nonetheless, Napoleon had once again inflicted a heavy loss on the primary Allied Army despite being outnumbered and for some weeks after Dresden Schwarzenberg declined to take offensive action.

[16] However at about the same time the French sustained several serious defeats, first at the hands of Bernadotte's Army of the North on 23 August, with Oudinot's thrust towards Berlin beaten back by the Prussians, at Großbeeren.

During a torrential rainstorm on 26 August, and due to conflicting orders and a breakdown of communications, MacDonald's several corps found themselves isolated from one another with many bridges over the Katzback and Neisse rivers destroyed by surging waters.

However, Ney blundered into a trap set by Bernadotte and was stopped cold by the Prussians, and then routed when the Crown Prince arrived with his Swedes and a Russian corps on their open flank.

News of Bernadotte's victory at Dennewitz sent shock waves across Germany, where French rule had become unpopular, inducing Tyrol to rise in rebellion and was the signal for the King of Bavaria to proclaim neutrality and begin negotiations with the Austrians (on the basis of territorial guarantees and Maximilian's retention of his crown) in preparation of joining the Allied cause.

Following a breakdown of negotiations, the armistice concluded and on 14 January 1814 Bernadotte invaded Schleswig, swiftly invested and reduced its fortresses and occupied the entire province.

Believing his primary goal of detaching Norway from Denmark and binding it with Sweden had been fully achieved, Bernadotte and the Swedish and Russian corps of his Army of the North advanced into and occupied the Low Countries.

Despite several attempts by the Russian General Bennigsen to storm the city, Marshal Davout held Hamburg for France until after Napoleon's abdication in April 1814.

[31] However, whilst Bernadotte cleared the Low Countries of the French in Spring 1814, the people of Norway objected to being bartered between kings, declared independence and adopted their own constitution on 17 May 1814.

[33] Norway agreed to enter into a personal union with Sweden as a separate state with its own constitution and institutions, except for the common king and foreign service.

While events unfolded in the East, the Peninsular War in Iberia continued to be Napoleon's "Spanish ulcer" tying down hundreds of thousands of French soldiers.

In the Battle of the Pyrenees Wellington fought far from his supply line but won with a mixture of manoeuvre, shock and persistent hounding of the French forces.

On 7 October, after Wellington received news of the reopening of hostilities in Germany, the Coalition allies finally crossed into France, fording the Bidasoa river.

During the last months of 1813 and into 1814 Wellington led the Peninsular army into south-west France and fought a number of battles against Marshals Soult and Suchet.

In early February Napoleon fought his Six Days' Campaign, in which he won multiple battles against numerically superior enemy forces marching on Paris.