Baldwin I was the first Emperor of the Latin Empire of Constantinople; Count of Flanders from 1194 to 1205 and Count of Hainaut from 1195 to 1205. Baldwin was one of the most prominent leaders of the Fourth Crusade, which resulted in the sack of Constantinople in 1204, the conquest of large parts of the Byzantine Empire, and the foundation of the Latin Empire. He lost his final battle to Kaloyan, the emperor of Bulgaria, and spent his last days as his prisoner.

The sack of Constantinople occurred in April 1204 and marked the culmination of the Fourth Crusade. Crusader armies captured, looted, and destroyed parts of Constantinople, then the capital of the Byzantine Empire. After the capture of the city, the Latin Empire was established and Baldwin of Flanders was crowned Emperor Baldwin I of Constantinople in the Hagia Sophia.