After the situation created in the Peninsula, after the consecutive defeats of his Armies and the escape toward the north of his brother, the King José Napoleon, the Emperor mobilized his tanned north armies, veterans of the wars of Germany, and under the command of his better generals he directed them and he concentrated in the Gironda. The composition of the army was the following one:

First Corp.- Marshal Víctor, Duke of Belluno.

 Second.- Marshal Soult, Duke of Dalmatia.

Third.- Marshal Moncey, Duke of Conégliano.

Fourth.- Marshal Lefebre, Duke of Danzick.

Fifth.- Marshal Mortier, Duke of Treviso.

Sixth.- Marshal Ney, Duke of Elchingen.

Seventh.- General Colonel Saint-Cir, in Catalonia.

Eighth.- General Colonel Junot, Duke of Abrantes.

Cavalry.- General Commander Marshal Bessières, Duke of Istria.

General Lasalle.

The army of reserve of Bayona to the orders of the Marshal Kellermann, Duke of Valmi.

The whole of the forces was ascending to approximately 250.000 soldiers and  50.000 horses, besides numerous pieces of artillery.

November 4th , 1808 the Emperor crosses the Bidasoa, sleeping that Night in Tolosa. The different bodies of army, that preceded him, they are distributed to be faced to the diverse Spanish armies. At first is the first body of army, to the command of the general Lefevre, the destined to regain Bilbao and to be faced to the Left’s Army.

 Lefebvre’s IV Corps included three infantry divisions and 36 cannon. Major-General Horace Sébastiani’s 1st Division contained the 28th Light and 75th Line (3 battalions) and the 32nd and 58th Line (2 bns.). Maj-Gen Leval’s 2nd Division was made up of 2 bns. each of the 2nd Nassau, 4th Baden and Hesse-Darmstadt Gross-und-Erbprinz Regiments, and the Paris National Guard and Frankfurt battalions.