Battle of Somosierra Historical milestone · Somosierra, Sierra Norte, Madrid Image of Somosierra, not of the place itself. On 30 November 1808 Napoleon sent the Polish lancers of his guard down the pass road against the batteries of General Benito de San Juan. The charge, extremely costly in lives, broke the Spanish defence and left the road to Madrid open. Although San Juan had chosen an extremely strong defensive position, the battle proved an inevitable French victory given the overwhelming superiority in numbers, training and combat experience of the Grande Armée. As a result, Madrid was left completely undefended: Napoleon besieged the city and bombarded it, and it surrendered unconditionally on 1 December 1808. 30 de noviembre de 1808 Photo: Cruccone (CC BY 3.0) What to see and do in Somosierra