Battle of Ocaña
The Battle of Ocaña was fought on 19 November 1809 between French forces under Marshal Jean-de-Dieu Soult against the Spanish army under General Juan Carlos Aréizaga, which suffered its greatest single defeat in the Peninsular War. General Aréizaga's Spanish army of 51,000 troops lost nearly 19,000 men killed, wounded, prisoners and deserters, mostly due to the French use of their cavalry.