What were the main grievances of the barons against King John?

The main grievances of the barons against King John were his heavy taxation, arbitrary justice, and military failures.

King John's reign from 1199 to 1216 was marked by numerous conflicts with his barons, who were the powerful landowners of medieval England. One of their primary complaints was the king's excessive taxation. John imposed heavy and frequent taxes to fund his military campaigns, especially his attempts to reclaim lost territories in France. These taxes were burdensome and often arbitrary, causing significant financial strain on the barons and their estates.

Another major grievance was John's abuse of the justice system. He was known for his arbitrary and often cruel administration of justice. The king would frequently manipulate the law to his advantage, using it as a tool to punish his enemies and reward his supporters. This lack of fair and consistent legal processes angered the barons, who felt their rights and privileges were being trampled upon.

Additionally, King John's military failures further eroded his support among the barons. His most notable defeat was the loss of Normandy to the French King Philip II in 1204. This loss not only diminished England's territorial holdings but also damaged John's reputation as a capable leader. The barons were frustrated by his inability to protect their lands and interests, both at home and abroad.

Moreover, John's personal behaviour and relationships with the barons were often problematic. He was known for his suspicious and vindictive nature, which led to a lack of trust and loyalty among his followers. His tendency to demand hostages from baronial families as a means of ensuring loyalty only deepened the resentment.

These grievances culminated in the barons' rebellion and the eventual sealing of the Magna Carta in 1215, a document that sought to limit the king's powers and protect the rights of the barons and other subjects.