into the Bulgarians' land: he was victorious and killed great number of them. He reached their capital, seized it and devastated it. His savagery went to the point that he ordered to bring their small children, got them tied down on earth and made thresh grain stones to smash them." While Nikephoros I and his army pillaged and plundered the Bulgarian capital, Krum mobilized as many soldiers as possible, giving weapons even to peasants and women. This army was assembled in the mountain passes to intercept the Byzantines as they returned to Constantinople. At dawn on 26 July, the Bulgarians managed to trap the retreating Nikephoros in the Varbitsa Pass. The Byzantine army was wiped out in the ensuing battle and Nikephoros was killed, while his son Staurakios was carried to safety by the imperial bodyguard after receiving a paralyzing wound to the neck. It is said that Krum had the Emperor's skull lined with silver and used it as a drinking cup. Conflict with Michael I Rangabe Staurakios was forced to abdicate after a brief reign (he died from his wound in 812), and he was succeeded by his brother-in-law Michael I Rangabe. In 812 Krum invaded Byzantine Thrace, taking Develt and scaring the population of nearby fortresses to flee towards Constantinople. From this position of strength, Krum offered a return to the peace treaty of 716. Unwilling to compromise from a position of weakness, the new Emperor Michael I refused to accept the proposal, ostensibly opposing the clause for exchange of deserters. To apply more pressure on the Emperor, Krum besieged and captured Mesembria (Nesebar) in the autumn of 812. In February 813 the Bulgarians raided Thrace but were repelled by the Emperor's forces. Encouraged by this success, Michael I summoned troops from the entire Byzantine Empire and headed north, hoping for a decisive victory. Krum led his army south towards Adrianople and pitched camp near Versinikia. Michael I lined up his army against the Bulgarians, but neither side initiated an attack for two weeks. Finally, on 22 June 813, the Byzantines attacked but were immediately turned to flight. With Krum's cavalry in pursuit, the rout of Michael I was complete, and Krum advanced on Constantinople. On the way, most of the fortresses, hearing about the strength of the Bulgarian army, surrendered without a fight. Only Adrianople resisted. The siege of this city was led by Krum's brother,