Siege of Pliska

In 811, the Byzantine emperor Nikephoros I Genikos assembled a huge army, estimated at about 70,000 soldiers and drawn from both his European and Asian forces, and began a campaign towards the Bulgarian capital of the time, Pliska. Taken by surprise, Krum offered the emperor peace, but Nikephoros firmly refused and continued his advance. On 17 June, Nikephoros's troops broke through the Bulgarian frontier defences in the narrow passes of the Balkan Mountains. A few days later, the Byzantines reached and besieged Pliska. 

The capital was subjected to plunder and destruction. The Byzantines treated the city's inhabitants with extreme brutality. The Bulgarian ruler Khan Krum again offered peace, but it was rejected once more. Krum was forced to leave the capital.