Simeon I of Bulgaria
After the Bulgarian victory in the war of 894–896, the Byzantines were forced to pay tribute to Tsar Simeon I of Bulgaria. In 912 when the Byzantine emperor Leo VI died, his brother Alexander refused to pay tribute to the Bulgarians. Simeon saw an opportunity to wage a new war and fulfill his ambitions to conquer Constantinople. Alexander died in the same year and the new government under the Patriarch Nicholas Mystikos made desperate attempts to avoid the war, promising that the infant Emperor Constantine VII would marry one of Simeon's daughters. At some point, the patriarch and Simeon even met outside the walls of Constantinople, performing a coronation ceremony. Thereafter, Simeon began using the title "Tsar of the Bulgarians", and the Greek title "basileus" in his seals.