Medieval kings were far likelier to be killed before clear succession rules
Between 600 and 1200, more than a fifth of Western Christian monarchs were killed by their own subjects. Over the next six centuries that share fell to about 6 percent. The historian Sverre Bagge credits a dull but powerful innovation: clear rules on who inherits the throne.
Regicide means deliberately killing a monarch, and the word can also name the person who does it. It joins Latin roots meaning of a king and killer. In British usage it has a narrower sense, the judicial execution of a king after trial, following the precedent of Charles I. Literature has long explored the idea, most famously in Macbeth's murder of King Duncan.
Scholars find it most common where succession is murky. Bagge counts 94 regicides in Western Christendom between 600 and 1200, or 21.8 percent of rulers, against 20 between 1200 and 1800. Firm inheritance rules made it hard to sweep aside a rightful heir and left only the nearest heir with a motive. A 2025 study of China from 1046 BCE to 1911 CE found that 35.7 percent of rulers died unnaturally, mostly at the hands of relatives, trusted ministers or invaders, and again unclear succession raised the risk. Other research links the killing of rulers to lost territory and weaker states, consistent with Steven Pinker's argument that stronger states reduce violence.
England and Scotland had plenty of precedents. Before the Tudors, Edward II and Edward V were murdered in captivity and Richard III fell in battle, while James III of Scotland died fighting rebels and Duncan II and James I were assassinated. The word itself spread among continental Catholics after Pope Sixtus V renewed the excommunication of Elizabeth I, calling her a crowned regicide for executing Mary, Queen of Scots, in 1587, two decades after Mary had given up her crown.
The defining English case came after the First English Civil War. Charles I, a prisoner insisting on his divine right, secretly tried to raise an army, and Parliament's leaders concluded that no deal was possible. On 13 December 1648 the Commons ended negotiations, and the army moved him from Carisbrooke Castle towards London. The Rump Parliament then created a High Court of Justice to try him for treason, a step Royalists considered unlawful because the Lords refused to pass it.
Source: Regicide
