Baldwin I (July 1172 – ), the first emperor of the Latin Empire of Constantinople, as Baldwin IX Count of Flanders and as Baldwin VI Count of Hainaut, was one of the most prominent leaders of the catastrophic Fourth Crusade, which resulted in the sack of Constantinople and the conquest of large parts of the Byzantine Empire, and the foundation of the Latin Empire, also known as Romània. He lost his final battle to Kaloyan, the emperor of Bulgaria, and spent his last days as his prisoner.