First Barons' War  The First Barons' War (1215–1217) was a civil war in the Kingdom of England in which a group of rebellious major landowners (commonly referred to as barons) led by Robert Fitzwalter with a French army under the future Louis VIII of France, waged war against King John of England. The war resulted from King John's refusal to accept and abide by "Magna Carta", which he had sealed on 15 June 1215. After John's death the ambitions of the French crown prince Louis to be King of England meant that many of the rebels switched sides and the war dragged on. The war ended after French defeats at Lincoln and Sandwich in 1217 and Louis was forced to sign the Treaty of Lambeth. This formalised the end of the civil war and the departure of the French from England. King John in June 1215 was forced to put his seal to "The Articles of the Barons" by a group of powerful barons who could no longer stand John's failed leadership and despotic rule. The king's Great Seal was attached to it on 15 June 1215. In return, the barons renewed their oaths of fealty to King John on 19 July 1215. A formal document to record the agreement was created by the royal chancery on 15 July: this was the original "Magna Carta". "The law of the land" is one of the great watchwords of "Magna Carta", standing in opposition to the king's mere will. The "Magna Carta" of 1215 contained clauses which in theory noticeably reduced the power of the king, such as clause 61, the "security clause". This clause allowed a group of 25 barons to override the king at any time by way of force, a medieval legal process called "distraint" that was normal in feudal relationships but had never been applied to a king. After a few months of half-hearted attempts to negotiate in the summer of 1215, open warfare broke out between the rebel barons and the king and his supporters. The war began over "Magna Carta" but quickly turned into a dynastic war for the throne of England. The rebel barons, faced with a powerful king, turned to Louis, son and heir apparent of King Philip II of France and grandson-in-law of King Henry II of England. The Norman invasion had occurred only 149 years before, and the relationship between England and France was not so simply adversarial as it later became.