1278

1278 (MCCLXXVIII) was a common year starting on Saturday of the Julian calendar, the 1278th year of the Common Era (CE) and Anno Domini (AD) designations, the 278th year of the 2nd millennium, the 78th year of the 13th century, and the 9th year of the 1270s decade. As of the start of 1278, the Gregorian calendar was 7 days ahead of the Julian calendar, which was the dominant calendar of the time.

Millennium:	2nd millennium
Centuries:	12th century – 13th century – 14th century
Decades:	1240s  1250s  1260s  – 1270s –  1280s  1290s  1300s
Years:	1275 1276 1277 – 1278 – 1279 1280 1281

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.