In the late 7th century CE, the semi nomadic Turkic Bulgars merged with the Vlach and Thracian people, were Slavicized, invaded the Byzantine Empire, and established the First Bulgarian Empire. A hundred years later, Nikephorus I Genik became Byzantine Emperor and after concluding peace treaties with Charlemagne and the Arabs, was determined reconquer the Bulgarian lands.
In 810, Nikephorus with a large Byzantine army of 60,000 invaded the Bulgarian Empire and expected an easy campaign. Initially he was not wrong and defeated the Bulgarians in two separate battles. But the pragmatic and wily Khan Krum knew he could not stand against the Byzantines in open battle and always managed to slip away before his army was completely destroyed. Three times Khan Krum tried to negotiate but the arrogant Nikephorus ignored him. In July, 811, the Byzantines captured, sacked, and razed Pliska, Krum’s capital. Confident in victory and heavily laden with slaves and plunder, the Byzantine Army withdrew back to Constantinople. However, Khan Krum had mobilized his entire people, and shadowed Nikephorus’ march home.
On 26 July 811, Khan Krum blocked the Byzantine Army in the Verbita Pass. As the Bulgar warriors descended on the column, the slaves taken at Pliska revolted, and the Byzantine Army broke. The Bulagrian people hunted down the routed troops, and in the ensuing massace, not a single Byzantine survived, including the emperor Nikephorus, his entire court, and most of his administration, all of whom went on the campaign expecting easy plunder.
After the battle was over, Krum had Nikephorus’ body found. He decapitated the corpse, and had the emperor’s skull bejeweled with the plunder taken from the Byzantine treasury and lined with silver. At the victory celebration, Khan Krum toasted his warriors and drank deeply from Nikephorus’ skull.
The Byzantines wouldn’t bother the Bulgarians for another hundred years.