678
year
Year 678 (DCLXXVIII) was a common year starting on Friday of the Julian calendar. The denomination 678 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
Events
By place
Byzantine Empire
July 27 – The Siege of Thessalonica (676–678) ends, when the Sclaveni withdraw.
Autumn – Siege of Constantinople: Emperor Constantine IV confronts the Arab besiegers in a head-on engagement. The Byzantine fleet, equipped with Greek fire, destroys the Muslim fleet at Sillyon, ending the Arab threat to Europe, and forcing Yazid (a son of caliph Muawiyah I) to lift the siege on land and sea. The victory also frees up forces that are sent to raise the two-year siege of Thessalonica by the local Slavic tribes.
Britain
King Æthelred of Mercia defeats the Northumbrian forces under King Ecgfrith, in a battle near the River Trent. Archbishop Theodore helps to resolve differences between the two, Æthelred agreeing to pay a weregild to avoid any resumption of hostilities (approximate date).
Japan
April 27 – Emperor Tenmu holds divination for the purpose of proceeding to the Abstinence Palace.
May 3 – Princess Tōchi suddenly takes ill and dies within the palace.
The public source identifies “678” as year. This brief keeps that definition visible, then builds a research path around year.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated May 1, 2026. The linked authority identifier is Q23448. None of the 0 selected statements returned an explicit reference.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
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Three-step research path
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Questions for further research
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This entry incorporates text from “678” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.