On this date over a millennium past, according to the chronicle of John of Wallingford, King Ethelred the Unready of England conducted a massacre of Danes living in the realm.

The character of this sanguinary event — named after a fourth-century French bishop whose feast day Nov. 13 happens to be — lies half-buried in history’s shifting sands. Surely the slaughter of every Dane in a Britain then very much in the Scandinavian orbit would have been not only morally reprehensible but logistically unimaginable.

The accepted, albeit sketchy, story has it that to consolidate his own authority — or to check an actual or suspected plot against him — Ethelred ordered the surprise apprehension and summary execution of some sizable number of Danish lords and mercenaries. British historian Thomas Hodgkin characterizes it as a sort of coup d’etat.

But whatever its true extent or immediate object, it occurred within the context of intensifying conflict between the English crown and Scandinavian aspirants. Ethelred was to spend the better part of his life struggling — both militarily and through the ruinous tribute of Danegeld — to hold back the incursions of the Viking king Sweyn I.

The St. Brice’s Day Massacre exacerbated those tensions. Sweyn’s sister was apparently among those massacred, and — whether driven by vengeance or simply availing a pretext — Sweyn resumed harrying the English kingdom in the following years.

By 1013, Sweyn had driven Ethelred to Normandy and ruled all of England, welding together a Norse empire fringing the whole north of Europe.

But the empire — and England’s place in it — proved an historical cul-de-sac. Authority in England would be contested for another half-century, gradually sapping the crown’s strength until the Norman Conquest in 1066 swept aside Viking power and set England on a course that would redefine its history.

Update: The story of Ethelred, Normandy, and the Vikings told in Episode 3 of Lars Brownworth’s Norman Centuries podcast:

[audio:http://c4.libsyn.com/editions/58550/17915/03-richard-the-good.mp3]

The British History Podcast covers the St. Brice’s Day Massacre in episode 328.

On this day..

• 1617: A miller of Manberna, the hangman's last
• 1951: Marcel Ythier, Andre Obrecht's first
• 1989: Rohana Wijeweera
• 1752: William Montgomery, small enough to fail
• 1544: Maria von Beckum and her sister-in-law Ursula
• 1765: Patrick Ogilvie, but not Katharine Nairn
• Announcing: Execution Playing Cards
• 1795: David McCraw, "blasted all our conjugal happiness"
• 2010: Farid Baghlani, womanslayer
• 1943: The Zalkind family
• Themed Set: Meaghan Good
• 1663: Corfitz Ulfeldt, in effigy
• 1676: Col. Thomas Hansford, the first American independence martyr
• 1534: Barthélemi Milon, for the Affair of the Placards
• 1849: Frederick and Marie Manning, a Dickensian scene