"siege" . "Bulgaria" . "Serdica, 809 Siege of" . "capture of Sofia" . "6,000" . "Unknown" . . . "Unknown" . "capturing the important city of Sofia" . . . "Serdica" . "besieged and forced the surrender" . . "Serdica (809), Siege of" . . . "seized the city" . . "Byzantine Empire" . . . "Siege of Serdica (Sofia)" . . . "Bulgarian Empire" . "Siege of Serdica" . "Siege of Serdica (809)" . . . "captured" . . "Siege of Serdica (809)" . . . . "Serdica in 809" . . . . "Siege of Serdica (Sofia" . "Bulgarian victory" . .