Leo the Deacon
At the news of this, a powerful Rus' force, along with many Bulgarians and a Pecheneg contingent, was sent south over the Balkan Mountains. After sacking the city of Philippopolis (modern Plovdiv) in Thrace, they bypassed the heavily defended city of Adrianople and turned towards Constantinople. The size of the Rus' army, and whether it comprised the entirety of Sviatoslav's forces or just a division, is unclear. John Skylitzes, for instance, implies that this was the entire Rus' army, numbering an incredible 308,000 men, but the contemporary Leo the Deacon reports that it was a detachment of "over 30,000 men"; conversely, the Russian "Primary Chronicle" gives the "entire" Rus' army under Sviatoslav at some 30,000, whilst numbering the Rus' at Arcadiopolis at only 10,000, faced with 100,000 Byzantines. It is clear, however, that the Byzantines were considerably outnumbered, and that the Rus' force at Arcadiopolis included significant numbers of Bulgarians, as well as allied contingents of Pechenegs and "Turks" (i.e. Magyars).