In 965 or 966, a
Bulgarian embassy visited the
Byzantine emperor Nikephoros II Phokas (r. 963–969) at
Constantinople to receive the annual tribute that had been agreed by the two powers as the price of
peace in 927. Phokas, flush and self-confident from a series of victories against the Arabs in the East that had led to the recovery of
Crete,
Cyprus, and
Cilicia, refused to comply, and even had the envoys beaten up. He followed this up with a show of military strength, by sending a small force to raze a number of Bulgarian border posts in
Thrace. . It was a clear declaration of war, but Nikephoros' forces were largely preoccupied in the East. Thus the emperor turned to the traditional Byzantine expedient of turning one of the peoples living further north, in modern-day
Ukraine, against Bulgaria. He sent an ambassador, the
patrikios Kalokyros, to
Sviatoslav, ruler of the
Rus' with whom the Byzantines had maintained close relations. Sviatoslav enthusiastically responded, and invaded Bulgaria in 967 or 968 in a devastating raid, before returning home to defend his capital against a
Pecheneg attack. This forced the Bulgarian tsar,
Peter I, to the negotiating table, agreeing to terms favourable to Byzantium. However, this brief sojourn also awakened in Sviatoslav the desire to conquer Bulgaria and establish his own realm there. He returned in force in July or August 969 and conquered the country within a few months. Nikephoros' scheme had backfired dramatically: instead of peace, a new and formidable foe had appeared in the
Balkans, and a large part of the Bulgarian nobility appeared to side with the Rus' prince. The emperor, however, was murdered in December 969, and it fell to his successor,
John I Tzimiskes (r. 969–976), to deal with the Rus' threat. Sviatoslav now turned his sights on Byzantium, and to John's entreaties for peace he allegedly answered that the Empire should abandon its European territories to him and withdraw to
Asia Minor. Tzimiskes himself was preoccupied with consolidating his position and with countering the unrest of the powerful
Phokas clan and its adherents, and delegated the war in the Balkans to his brother-in-law, the
Domestic of the Schools Bardas Skleros, and to the eunuch
stratopedarches Peter. They were to winter in Thrace and raise an army, whilst sending spies to discover Sviatoslav's intentions. 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.
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). ==The battle==