The king of Bulgaria, who invaded Constantinople four times. In 893, Simeon succeeded the Bulgarian throne. The ambitious Simeon had a clear goal, which is the crown of the Roman emperor. In the midsummer of 917, Simeon led 60,000 troops to invade the Byzantine Empire. After the victory in the Battle of Achelous, he marched to Constantinople, the most solid city in the middle ages. Although it failed to break the wall of Constantinople, the Bulgarian army had already swept through the Byzantine territory, and shredded the dignity of Byzantine Empire. In the following five years, the Bulgarian army came to Constantinople four times. In 925, Simeon ignored the Byzantine people's protest and declared that the Byzantines became his own people, proclaiming himself the Emperor of the Romans and Bulgarians. Simeon became the undisputed overlord of Southeast Europe.