The Spanish conventional warfare had started at El Bruch (June 1808), while the Battle of Bailen (July 1808) marked the first open-field defeat of a Napoleonic army.

Under Napoleon's guidance, the French had made meticulous preparations to defeat Blake's position and thereby beat the left wing of the Spanish front that stretched from Cantabria to the Mediterranean Sea.

[1] On October 31, 1808, Marshal François Lefebvre bloodied the Army of Galicia under Lieutenant General Joaquín Blake but failed to encircle or destroy it, upsetting both the Emperor and the French strategic situation.

The Spanish infantry, fighting without artillery support, was swiftly thrown back but escaped in good order.

Ultimately, however, the overwhelming strength of Napoleon's Grande Armée allowed the French to sweep past the tottering Spanish defences and capture Madrid by year's end.