878

878 in various calendars
Gregorian calendar	878; DCCCLXXVIII
Ab urbe condita	1631
Armenian calendar	327; ԹՎ ՅԻԷ
Assyrian calendar	5628
Balinese saka calendar	799–800
Bengali calendar	285
Berber calendar	1828
Buddhist calendar	1422
Burmese calendar	240
Byzantine calendar	6386–6387
Chinese calendar	丁酉年 (Fire Rooster); 3575 or 3368; — to —; 戊戌年 (Earth Dog); 3576 or 3369
Coptic calendar	594–595
Discordian calendar	2044
Ethiopian calendar	870–871
Hebrew calendar	4638–4639
Hindu calendars
- Vikram Samvat	934–935
- Shaka Samvat	799–800
- Kali Yuga	3978–3979
Holocene calendar	10878
Iranian calendar	256–257
Islamic calendar	264–265
Japanese calendar	Gangyō 2; (元慶２年)
Javanese calendar	776–777
Julian calendar	878; DCCCLXXVIII
Korean calendar	3211
Minguo calendar	1034 before ROC; 民前1034年
Nanakshahi calendar	−590
Seleucid era	1189/1190 AG
Thai solar calendar	1420–1421
Tibetan calendar	阴火鸡年; (female Fire-Rooster); 1004 or 623 or −149; — to —; 阳土狗年; (male Earth-Dog); 1005 or 624 or −148

Millennium:	1st millennium
Centuries:	8th century; 9th century ; 10th century;
Decades:	850s; 860s; 870s ; 880s; 890s;
Years:	875; 876; 877; 878 ; 879; 880; 881;

Year 878 (DCCCLXXVIII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar.

Events

January 6 – King Alfred the Great is surprised by a Viking attack at Chippenham. He is forced to flee, with his family, into the Somerset Levels for safety. From his headquarters at Athelney, Alfred wages a guerrilla war against the Vikings.
May – Battle of Edington: Supported by all the levies of Somerset, Wiltshire and Hampshire, Alfred the Great decisively defeats the main body of Danish Vikings, led by King Guthrum, at present-day Edington (near Bratton Castle).
Treaty of Wedmore: Guthrum agrees to a peace treaty and is baptised, taking the name of Aethelstan. England is divided between Wessex in the south, and the Vikings in the Danelaw up north. Guthrum returns to East Anglia.
Battle of Cynwit: Viking raiders, led by Ubba Ragnarsson, land on the coast at Combwich with 23 ships, and besiege a hillfort (called Cynwit) at Cannington. Ealdorman Odda launches a surprise attack, and kills Ubba in battle.^[1]
King Rhodri the Great of Gwynedd, Powys and Seisyllwg, returns to his kingdoms, but is killed fighting the Mercians of King Ceolwulf II. His kingdoms are divided amongst his three sons: Anarawd, Merfyn and Cadell.
King Áed I of Scotland is killed in battle, by his rival Giric mac Dúngal. Giric becomes king of the Picts, and allies himself with Eochaid (grandson of Kenneth I). The two rule all of Alba (Scotland) together as joint-kings.

May 21 – Siege of Syracuse: The Aghlabids capture the Byzantine fortress city of Syracuse, after a nine-month siege. Most of the population is massacred by the Arabs.
Zanj Rebellion: The Zanj (black slaves from East Africa) in Mesopotamia seize Wasit (modern Iraq), and establish a presence in the Persian province of Khuzestan.
King Alfonso III of Asturias conquers the city of Coimbra (modern Portugal), which is under Umayyad reign.^[2]

April 16 – The city of Belgrade is first mentioned in a papal letter to Boris I, ruler (khan) of the Bulgarian Empire.
September 7 - Pope John VIII crowns Louis the Stammerer as king of the West Frankish Kingdom, in the cathedral at Troyes.
The excommunication of the later pope Formosus is lifted, after he has promised never to return to Rome.

^ Paul Hill (2009). The Viking Wars of Alfred the Great, pp. 73–76. ISBN 978-1-59416-087-5.
^ Picard, Christophe (2000). Le Portugal musulman (VIIIe-XIIIe siècle0. L'Occident d'al-Andalus sous domination islamique. Paris: Maisonneuve & Larose. p. 109. ISBN 2-7068-1398-9.