Abstract
This article's main aim is to summarise the crucial period of the reign of King John of England during so-called first barons' war of 1215 - 1217 and through the examination of contemporary sources show possible attitudes to the invasion of Prince Louis of France in 1216, when he was invited by English barons to become their new king, which eventually turned to the usurpation when King John died and his son Henry became king of England with support of those who had been adherents of Louis before. In June 1215, English barons persuaded King John to agree with terms of Magna Carta, limiting royal power in various branches of law.
When Magna Carta was proclaimed null and unlawful by Pope Innocent III allowing John not to be bound by its terms, it meant open war with English rebels. They negotiated an invasion of Prince Louis, the eldest son of Philip II, king of France, and they promised him a crown of England.
In October 1216, King John suddenly died in the middle of war and he was succeeded by his son Henry. Henry III was in relatively short time accepted by most of rebellious barons leaving Louis in very precarious situation and it eventually led to Louis' defeat in 1217.
The treaty of Lambeth (September 1217) ended this war with Plantagenets still on English throne.