1278

Events 
 August 26 – Kings Rudolph I of Germany and Ladislaus IV of Hungary defeat King Otakar II of Bohemia in the Battle of Marchfield, a match of over 80,000 men and the largest battle of knights in the Middle Ages. The battle ends a power struggle between Rudolph and Otakar over the fate of central Europe, and Rudolph's Habsburg family will continue to rule Austria and other captured territories until the end of World War I in 1918.
 The independence, boundaries, and political structure of Andorra are agreed to by the Spanish Bishop of Urgell and the French Count of Foix.
 The earliest known written copy of the Avesta, a collection of ancient sacred Persian Zoroastrian texts previously passed down orally, is produced.
 An edict by Pope Nicholas III requires all Jews to attend conversion sermons.
 The Japanese era Kenji ends, and the Koan era begins.