Christian feast day: Boris I of Bulgaria (Bulgarian Orthodox Church)

Boris I, venerated as Saint Boris I (Mihail) the Baptizer, was the ruler (knyaz) of the First Bulgarian Empire from 852 to 889. Despite a number of military setbacks, the reign of Boris I was marked with significant events that shaped Bulgarian and European history. With the Christianization of Bulgaria in 864, paganism was abolished. A skillful diplomat, Boris I successfully exploited the conflict between the Patriarchate of Constantinople and the Papacy to secure an autocephalous Bulgarian Church, thus dealing with the nobility's concerns about Byzantine interference in Bulgaria's internal affairs.

The Bulgarian Orthodox Church, legally the Patriarchate of Bulgaria, is an autocephalous Eastern Orthodox jurisdiction based in Bulgaria. It is the first medieval recognised patriarchate outside the Pentarchy and the oldest Slavic Orthodox church, with some 6 million members in Bulgaria and between 1.5 and 2 million members in a number of other European countries, Asia, the Americas, Australia, and New Zealand. It was recognized as autocephalous in 1945 by the Ecumenical Patriarchate of Constantinople.