Excerpts from Books and Wikipedia
"Beginning of the decline of the Latin Empire." [Timeline of Middle Ages] "The Latin Empire, also referred to as the Latin Empire of Constantinople, was a feudal Crusader state founded by the leaders of the Fourth Crusade on lands captured from the Byzantine Empire. The Latin Empire was intended to replace the Byzantine Empire as the Western-recognized Roman Empire in the east, with a Catholic emperor enthroned in place of the Eastern Orthodox Roman emperors." [Wikipedia] "The Battle of Adrianople occurred around Adrianople on April 14, 1205 between Bulgarians, Vlachs and Cumans under Tsar Kaloyan of Bulgaria, and Crusaders under Baldwin I, who only months before had been crowned Emperor of Constantinople, allied with Venetians under Doge Enrico Dandolo. The battle was won by the Bulgarian Empire after a successful ambush." [Wikipedia]