The Byzantines plundered and burned the Bulgar capital Pliska which gave time for the Bulgarians to block passes in the Balkan Mountains that served as exits out of Bulgaria.

[4] That attempted attack, however, gave reason for the Bulgar Khan, Krum, to undertake military operations against the Byzantine Empire.

The Bulgar troops captured 1,100 litres (roughly 332 to 348 kilograms)[5] of gold and killed many enemy soldiers including all strategoi and most of the commanders.

The conquest was supposed to be easy, and many high-ranking officials and aristocrats accompanied Nicephorus, including his son Stauracius and his brother-in-law Michael I Rangabe.

Krum assessed the situation, estimated that he could not repulse an army of such size and offered peace, which Nicephorus haughtily rejected.

The Byzantine soldiers looted and plundered; burnt down the unharvested fields, cut the tendons of the oxen, slaughtered sheep and pigs.

[15] While Nicephorus and his army were busy plundering the Bulgarian capital, Krum mobilized his people (including women and Avar mercenaries[16]) to set traps and ambushes in the mountain passes.

[18] Initially Nicephorus intended to march through Moesia and reach Serdica before returning to Constantinople but the news of these preparations for a battle changed his decision and he chose the shortest way to his capital.

[19] The overconfident Emperor neglected to scout ahead and on 25 July the Byzantine army entered the Vărbitsa Pass.

The Byzantine cavalry, however, told Nicephorus that the road was barred with wooden walls and that Krum's forces watched from the surrounding heights.

From the heights, the Bulgarian troops began an effort to taunt and unsettle the Byzantine forces by means of banging their shields.

Unable to quickly ford the river, many of the Byzantines including mounted forces fell into the water and became stuck in the mud.

Those Byzantines who made it across the river were later confronted by high moated wooden walls constructed by the Bulgarians to impede the pathways to the south.