Khan Krum was in power from 803 to 814. He layeth the smack down on Byzantine!
But first, Khagan Krum joined forces with the Frankish empire of Charles the Great and destroyed the Avar Khanate. Krum annexed the Avar Khanate's lands and incorporated Transylvania into Bulgaria; in 812 he pushed the frontiers of his domain all the way north to the Tisza {or Tisa, or Theiss} River. Thus Bulgaria's territory was expanded to cover the lands between the Danube and the Carpathians. A common border was established with the empire of Charles the Great and Bulgaria became an outstanding power in Europe. It is understandable that now the Byzantine emperor felt very alarmed.
Nicephorus I Genik's planned campaign against Bulgaria was prevented by infighting amongst the Byzantines. But Khagan Krum wasn't going to sit still and wait, attack is the best means of defense. In 808-809 the Khan's soldiers defeated the Byzantine army in the Struma valley, seizing an immense loot and much gold. The defenders of Sredets {Serdika} laid down their arms and surrendered the town which was later to become Bulgaria's capital. Not long after that Nish and Belgrade fall into the hands of the Bulgarians. Krum was ready to march on Macedonia.
Nicephorus I made a retaliatory move when in 811 the Byzantine army crossed the Balkan range through unguarded side passes and headed towards the capital, Pliska. The Khan was not in Pliska at that moment, he had his hands full with a war on Bulgaria's eastern frontier. After a fierce battle over Pliska the Bulgarians were forced to retreat. The Byzantines slayed women, children and old people, burned the capital and destroyed the Khan's palace. Despite all of that, Krum sent the following message to the basileus: "Alright, you won. Take what you please and go in peace." But Nicephorus rejected the proposal.
Vengeance time! The Khan quickly defeated his enemies on the eastern frontier and turned west to meet Nicephorus. In the mean time, Nicephorus had happily continued his pillaging and managed to work his way into one of the Balkan passes. Khagan Krum positioned his army on the high ridges above the pass and during the night of the 25th. of July they laid siege on the Byzantine army in the Vurbitsa pass. The Byzantines were crushed like never before. The Emperor and most of his commanders were killed. One Byzantine historian remarked that Nicephorus and his soldiers could not have escaped Krum's attack even if they had turned into birds. To celebrate his victory, the Khan had the emperor's skull lined with silver and made into a vine cup. He drank from it when he hosted the Slavic princes, at his palace.
Having taken his revenge, Krum proposed peace. When met with a refusal, he led his army south to the area between the Struma and the Maritsa, seizing Byzantine towns and strongholds. The population was sent to territories beyond the Danube, so as to incorporate new lands more easily into the Bulgarian state. Then Krum extended another proposal for peace. Despite his victories, he set a very modest condition: renewal of the treaty from Khan Tervel's time. When the new emperor refused, the Bulgarians turned on the fortress of Messembria {Nessebar}. A memorable battle was fought by the town of Versinikia, not far from Adrianople, on 22 June 813. Once again the Byzantine army was routed and the Khan triumphed. Bulgaria had Thrace and Northern Macedonia detached from the empire of the Romans.
Having besieged Adrianople, in a few days the Bulgarians reached the walls of Constantinople, filling the hearts of Byzantines in the besieged capital with horror. The emperor proposed peace negotiations with the perfidious intention to kill the Bulgarian Khan. Krum avoided the trap but was enraged by the Emperor's plot. And now Krum was going to teach the Romans a very important lesson: Don't mess with the Khan! The Bulgarians ravaged the lands between Constantinople and Adrianople, looting and taking prisoners. Adrianople fell, giving Krum the nickname of Strashny {the Terrible}: a stern ruler, merciless to his enemies.
In 813 Krum's army stood outside the walls of Constantinople, but the Khan's sudden death {brain anurism? hart attack?} on 13 April 814 prevented the Bulgarians from sacking Constantinople, the planed attack was never initiated.
Khagan Krum's most important contribution to Bulgaria was probably - Bulgaria's first written laws. Khan Krum's laws protected private property and made slander and drinking severely punishable. His laws were applicable to all Bulgarians and ensured subsistence to beggars and unique state protection to the poor. Krum's laws allowed him to unite Bulgarians and Slavs into a strong, integrated and centralized state and gained him the reputation of a remarkable and magnanimous ruler. Starting with Khan Asparuh, the Bulgars knew that if their state was to survive, they had to forge Slavs, Thracians and Bulgars into one nation. Krum's son Omurtag would continue this task.
