Year 1215 (MCCXV) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. Events By place England March 4 – King John (Lackland), hoping to gain the support of Pope Innocent III against the Barons, takes the oath to go on Crusade. By doing so, Innocent declares John to be his vassal and claims ownership of the whole kingdom (with political protection under church law). On April 1, Innocent sends a letter to the Barons, asking them to halt their actions against John. May 5 – Robert Fitzwalter is elected by the Barons as their general, with the title of "Marshal of the Army of God and Holy Church". He solemnly renounces his homage to John (Lackland) and begins to siege Northampton Castle. While this failed, Robert consolidates his forces. He turns to Prince Louis of France, son and heir apparent of King Philip II (Augustus) for support. May 17 – The gates to London are opened by supporters of the rebellious Barons. The houses of Jews are targeted for ransacking and burning. The rebels, under Robert Fitzwalter, call for the English nobles still on the side of John (Lackland) to join them, and repair the walls. The Tower of London, held by John's supporters, is too well defended to fall into the hands of the rebels. June 15 – A large number of barons, led by Stephen Langton, archbishop of Canterbury, meet John (Lackland) on an island in the Thames at Runnymede. They force John to sign the Magna Carta, a document that grants liberties to the "free men" – the Barons, the church and the towns. He is subjected to the rule of law, by confirming the status of trial by jury, on June 19. August – John (Lackland) rejects the Magna Carta and writes to Innocent III – asking him to cancel the charter on grounds that he signed it against his will. At the same time, John continues to build up his mercenary army. September 13 – John (Lackland) seeks help from Innocent III in his fight against the Barons. In a letter, written while staying at Dover Castle, he states that the defense of England is the responsibility of God and the Pope. October – The Barons offer the English crown to Louis of France and invite him to England. John (Lackland) confiscates the Barons' land and besieges