The Battle of Edirne

The Byzantine Empire fell during the Fourth Crusade, and Byzantine aristocrats founded the Empire of Nicaea. Despite its name, it was less an empire than a fortress of paramount importance. Theodore II Laskaris came to power there in 1254. Bulgarian forces were entering the Rhodope region and Macedonia at the time.

Bulgaria suffered defeat, and its lands in the Rhodope Mountains and Macedonia fell under Nicaean rule. A few years later, the Byzantines conquered all of Thrace.