Nikephoros I overthrew the empress Irene, reformed the empire's finances with a rigour that made him hated, and was killed by the Bulgars in 811 — the first emperor to die in battle against a foreign enemy since 378.
Nikephoros was the general logothete — effectively the empire's finance minister — under the empress Irene, and in October 802 he overthrew her.
What followed was eight years of unpopular competence. He reversed the tax remissions that had made Irene popular and the treasury empty, taxed the church and the monasteries, tightened collection, and restored imperial authority in a Balkan peninsula that had slipped largely out of Byzantine control.
In 811 he invaded Bulgaria, took and burned the capital Pliska, and was caught in the Varbitsa Pass on the way home. He and most of his army were killed, and Khan Krum had his skull made into a drinking cup.
He came from Seleucia in Pisidia and, by his own family tradition, from Arab royal descent through the Ghassanid line — a claim the sources report and cannot verify.
His career was in the treasury rather than the army, which makes his later personal command of a Balkan campaign a considerable gamble on his own account.
By 802 he held the empire's senior financial office under an empress whose fiscal policy he must have regarded as ruinous, which is the ordinary and sufficient explanation for the coup.
The chronicler Theophanes hated him and is the main source, so the portrait needs handling: Nikephoros taxed the monasteries, and Theophanes was a monk.
What Theophanes gives is a grasping, irreligious tyrant with a list of "ten vexations" — the fiscal measures, enumerated as crimes. Read as a description of policy rather than of character, the list is actually a summary of a coherent and rather impressive programme of financial reconstruction.
What can be said independently is that he was personally brave, took the field himself against an enemy that had destroyed reputations, and pressed a campaign further than prudence allowed. The Bulgarian invasion of 811 was daring and it was his own decision, and it killed him.
The financial programme was the substance of the reign. He restored the taxes Irene had remitted, made the church and monasteries pay, reformed the assessment of land, and regulated shipping loans and the coinage.
In the Balkans he did what no emperor had managed since the Slavic settlement: campaigns in Greece, the re-establishment of themes in the Peloponnese, and the systematic resettlement of Greek-speaking populations into areas that had slipped from imperial control. The recovery of Greece for Byzantium begins here.
He also faced Krum, who had unified the Bulgars and taken Serdica in 809. Nikephoros invaded in 811, defeated the Bulgar forces, took Pliska and burned it, and rejected Krum's offers of peace.
The Bulgars blocked the passes behind the returning Roman army with wooden palisades and fell on the camp at night on 26 July 811.
The army was destroyed. Nikephoros was killed, his son Staurakios was wounded so badly that he was paralysed, and much of the empire's command structure died in the pass.
Krum had the emperor's skull cleaned, lined with silver, and used as a drinking cup at feasts — an act the Byzantine tradition never forgot and which appears in this archive's article on the First Bulgarian Empire. Nikephoros was the first Roman emperor killed by a foreign enemy in battle since Valens at Adrianople in 378.
The finances he restored funded the empire through the following decades, and the Balkan resettlement is the foundation of the Byzantine recovery of Greece — both durable achievements that his hostile chronicler recorded as offences.
The disaster of 811 cost the empire an emperor, an army and a generation of confidence in the Balkans, and it made Krum the most dangerous enemy the empire faced in Europe until Symeon a century later.
His son survived him by two months, and the dynasty ended with his son-in-law Michael I two years later.