Bailén, or Baylén, a town of southern Spain, in the province of Jaén; 21 m. by road N. of the city of Jaén. Pop. (1900) 7420. Bailén is probably the ancient Baecula, where the Romans, under P. Cornelius Scipio the elder, signally defeated the Carthaginians in 209 and 206 B.C. In its neighbourhood, also, in 1212, was fought the great battle of Las Navas de Tolosa, in which, according to the ancient chroniclers, the Castilians under Alphonso VIII, slew 200,000 Moors, and themselves only lost 25 men. Although this estimate is absurd, the victory of the Christians was complete. The capitulation of Bailén, signed at Andújar by the French general Dupont, on the 23rd of July 1808 after several days' hard fighting, involved the surrender of 17,000 men to the Spaniards, and was the first severe blow suffered by the French in the Peninsular War.