. "laying siege" . . "combined effort" . . . "Byzantine Empire" . "Thessalonica, 617 Siege of" . "Avars" . . . . . "617/618" . . . . . "month-long siege of the city" . "Siege of Thessalonica (617)" . "617" . "unsuccessful siege" . . "Siege of Thessalonica" . "Sclaveni" . "Siege of Thessalonica (617)" . "Siege of Thessalonica (604)" . . . . . "Successful defence of Thessalonica" . "Thessalonica" .