How did King John fight the barons after the Magna Carta was sealed?

After the Magna Carta was sealed in June 1215, the agreement quickly proved unworkable due to the intransigence of some barons and King John’s immediate appeal to Pope Innocent III to annul it. The Pope sided with the king, declaring the charter null and void, which effectively triggered the First Barons' War.123

To fight the rebels, King John employed several military strategies:

• Military Campaigns: John actively waged war by capturing Rochester Castle and laying waste to the northern counties and the Scottish border.1
• Papal Support: By securing the Pope's backing, John gained a powerful ecclesiastical ally who excommunicated the rebellious barons, undermining their moral and political standing.23
• Vigorous Warfare: Despite the arrival of Prince Louis VIII of France, who had been invited by the barons to invade England, John continued to wage war vigorously until his death in 1216, leaving the conflict at an inconclusive stage.12

Ultimately, the war continued until after John's death, when a compromise was reached under his son, Henry III.12