"The King is dead, long live the King!", or simply "Long live the King!", is a traditional proclamation made following the accession of a new monarch in various countries. The seemingly contradictory phrase is used to simultaneously announce the death of the previous monarch and assure the public of continuity by saluting the new monarch.
In modern times, this phrase has become a popular phrasal template. Given the memorable nature of the phrase (owing to epanalepsis), as well as its historic significance, the phrase crops up regularly as a headline for articles, editorials, or advertisements on themes of succession or replacement. Robert Cecil, one of the architects of the League of Nations, famously concluded his speech at the final session of the League of Nations with the phrase: "The League is dead. Long live the United Nations."
The original phrase was translated from the French Le roi est mort, vive le roi!, which was first declared upon the accession to the French throne of Charles VII after the death of his father Charles VI in 1422. In France, the declaration was traditionally made by the duc d'Uzès, a senior peer of France, as soon as the coffin containing the remains of the previous king descended into the vault of Saint Denis Basilica. The phrase arose from the law of le mort saisit le vif—that the transfer of sovereignty occurs instantaneously upon the moment of death of the previous monarch. "The King is dead" is the announcement of a monarch who has just died. "Long live The King!" refers to the heir who immediately succeeds to a throne upon the death of the preceding monarch.
At the time, French was the primary language of the nobility in England, and the proclamation was quickly taken up as ideally representing the same tradition—which in England dates back to 1272, when Henry III died while his son, Edward I, was fighting in the Crusades. To avoid any chance of a civil war erupting over the order of succession, the Royal Council proclaimed: "The throne shall never be empty; the country shall never be without a monarch." Thus, Edward was declared king immediately, and he reigned until news of his father's death reached him and he returned to England. Another example is among the French royalty. In France, Louis XV was the predecessor of Louis XVI. Upon Louis XV's death at around 11:00 pm on 10 May 1774, heir-apparent Louis-Auguste, le Dauphin, immediately became King Louis XVI of France. This quick transition of sovereignty was made within the phrase "The King is dead, long live The King!"