Short answers, pulled from the story.
The Spanish Army of Andalusia, commanded by General Francisco Javier Castaños, won the Battle of Bailén. The French force under Divisional-General Pierre Dupont de l'Etang surrendered on the 19th of July 1808, with approximately 17,000 French soldiers taken prisoner.
Bailén was the first open-field defeat of a Napoleonic army, and the first time since 1801 that a sizable French force had surrendered. The victory shattered the legend of French invincibility, inspired Austrian Emperor Francis to challenge Napoleon in the War of the Fifth Coalition, and prompted Napoleon to personally lead the Grande Armee into Spain.
The surrender terms promised repatriation to France, but Spain did not honor them. Most prisoners were held on prison hulks in Cadiz harbour, then transferred to the uninhabited island of Cabrera in the Balearics. On the 6th of July 1814, the surviving prisoners returned to France, but fewer than half of the original 17,000 captives were still alive.
General Reding, Governor of Malaga, commanded the Spanish division that crossed the Guadalquivir at Mengibar, seized the town of Bailen, and drew up the defensive line that repulsed three French assaults on the 19th of July 1808. His maneuver cut off Dupont's line of retreat to the Sierra Morena. Reding later died of wounds received when he was ridden down by French cavalry at the Battle of Valls in 1809.
Dupont returned to Paris in disgrace, was court-martialled, deprived of his rank and title, and imprisoned at Fort de Joux. He was not paroled until the restoration of Louis XVIII. Napoleon also issued an Imperial decree dated the 1st of May 1812 making every unauthorized surrender a criminal act punishable by death.
Dupont's force was composed mainly of inexperienced second-line troops originally intended for garrison duty. After plundering Cordoba, the army retreated burdened with more than 500 wagons of loot and 1,200 sick men. A French surgeon attached to the campaign noted that their movements were entirely impeded, attributing the defeat to the greed of their generals. Miscommunication between Dupont and Vedel's division also left the French dangerously scattered on the day of battle.