King Louis Bonaparte sent the brigade in September 1808, to take part in the Peninsular War on the French side at the request of his brother Emperor Napoleon of France.

On 17 August 1808, Emperor Napoleon of France sent a peremptory demand to his brother, King Louis of Holland, to furnish a brigade for service in the campaign in Spain.

The Minister of War, General Janssens, and the Commander-in-Chief, Marshal Dumonceau, recommended Major-General David Hendrik Chassé as commander of the newly created brigade.

Finally, Napoleon organised two depots, one for the infantry in Saint-Denis, and another for the cavalry in Versailles, where stragglers and sick personnel (208 men, among whom was Major Steinmetz) were to be collected for eventual transfer to their units in Spain.

[1]: 64–76 Almost immediately after the brigade's arrival on Spanish soil, Marshal Lefebvre took away General Chassé's miners, sappers, cavalry and artillery.

Villatte let them attack the Spaniards by moving uphill and, despite the difficult terrain, they first succeeded in driving the Spanish from the hillock of Bernagoitia, and then Nevera.

[1]: 84–90 The logistical problems that plagued the entire Iberian army, were felt even more keenly by the Dutch, as they were supplied only after the French needs were fulfilled.

The younger officers blamed Chassé for being insufficiently forceful in his representations to the French corps command, and they openly showed their displeasure making personal relations with the general difficult.

The brigade received orders to guard one of the three bridges across the Tagus river, at El Puente del Arzobispo, where they arrived at the end of January.

The Dutch hussars remained with IV Corps, now commanded by General Sébastiani, and took part in, among others, the battle of Ciudad-Real of 27 March 1809, in which Colonel Roest van Alkemade was mentioned in despatches.

[1]: 97–103 Meanwhile, the Dutch infantry fortified the bridge at Arzobispo under the direction of engineer officers Van Schelle and De Boer, making it impassable.

The local guerillas, about 10,000 in number, were mostly escaped prisoners of war, former soldiers of the army of General Venegas, who had been defeated by Marshal Victor at the Battle of Uclés (1809).

The Dutch Brigade became involved in a reprisal against the town of Arenas de San Pedro, where the inhabitants had murdered a number of Westphalian dragoons, and mutilated their bodies.

[Note 6] After the Second Siege of Zaragoza had ended with a French victory on 24 February 1809, Marshal Victor decided to attack the Spanish forces on the south bank of the Tagus.

Quartermaster Romar therefore organized a military bakery and butchery, with Dutch bakers and butchers recruited from the ranks, to take care of the brigade's needs.

The battle ended in a tactical draw, but the British retreated to Badajoz, rebuffing offers from the Spanish to pursue as they did not trust their allies to provide sufficient supplies.

On 11 August 1809, IV Corps left Toledo to cut off the advance of the Spanish army of General Venegas marching to Madrid.

King Louis was so pleased with the Dutch contribution to the victory that he authorized that every year of service in the campaign in Spain would count double.

On the contrary, the Netherlands itself was involved in war due to the British landing in Zeeland, and King Louis demanded the recall of the brigade to help defend the Fatherland.

In addition he asked for understanding of the difficult circumstances under which he had to work: supplies were lacking; clothing, shoes and medications were not available; and weakened soldiers were unable to keep up with the marching tempo.

The French could not allow this, and on 9 November Marshal Soult ordered Polish hussars, reinforced by the horse artillery of Captain Trip, to occupy the town of Ocaña.

The Poles and Dutchmen won, but the event was worrisome enough to the French command that it ordered all available units across the Tagus to stem the Spanish advance.

[1]: 138–139 On 18 November, Chassé, ordered to march overnight with the Dutch Brigade and the Polish cavalry from Aranjuez to Ocaña, arrived at daybreak.

Soult's opening move was an assault by the French left wing, consisting of Polish, German and Dutch troops, on the Spanish right.

[6]: 35  The allied soldiers managed to infiltrate the ranks of the Spanish infantry, and man-to-man fights ensued which put the Spaniards on the defensive.

The Dutch brigade was generally unsuccessful, too, though Captain J. P. Sprenger, with a detachment of 100 men, defeated a troop of 900 Spanish irregular cavalry near Lerma on 24 January.

In mid-April 1810, Chassé established his headquarters in Almagro and managed to capture a flock of 15,000 merino sheep being driven to Portugal by guerrillas on orders of the Junta Central.

In mid-June, he arrived with the severely depleted brigade (only 600 men, 260 horses and two guns were left) in Manzanares to fight the local guerrillas, but his troops were too exhausted to do anything noteworthy.

[1]: 169–179  Meanwhile, the other, newly formed battalions of the 123rd regiment, augmented with new Dutch conscripts, became part of the army with which Napoleon invaded Russia in June 1812.

Not surprisingly, he ordered a bayonet charge, which he led on horseback, with the brigade-Detmers, supposedly on the French Middle Guard, but possibly on troops of the brigade commanded by general Jean Gaudens Claude Pégot, in a decisive phase of the battle[citation needed].