The Byzantine emperor Basil I (ca. 812-886), also known as Basil the Macedonian, ruled from 867 to 886. Despite his unsavory rise to power, he was a gifted statesman who gave the empire new vigor and began its most durable dynasty.

Of obscure Armenian parentage, Basil was born in Thrace. According to one tradition, he was carried off into captivity by the Bulgars while an infant; escaping in his 20s, he sought his fortune in Constantinople and took service with a kinsman of the Caesar Bardas, uncle and guiding influence of Emperor Michael III. About 858 Basil attracted the attention of the Emperor through his great physical strength and his way with horses. He rapidly rose to high ranks, became Michael's boon companion, and in an arrangement of convenience married the Emperor's mistress.

Basil's influence grew, and his ambition was kindled. In May 866 Michael proclaimed Basil his co-emperor. Allegedly because of...