Did you know that King John’s barons offered the English throne to Prince Louis of France? 
The barons threatened King John and forced him to agree to the rules set out in Magna Carta, but John had written to the pope. When the pope heard about Magna Carta, he promptly anulled it. ‘Under threat of excommunication we order that the king should not dare to observe and the barons and their associates should not insist on it being observed. The charter with all its undertakings and guarantees we declare to be null and void of all validity for ever’ he wrote. On 5 September 1215 the pope’s representatives excommunicated the rebel barons.
Frustrated, the barons went to war again, but this time went one step further. The problem with their rebellion, was that previous rebellions had been in support of a rival candidate, but they had no alternative candidate for the throne. King Philip of France’s son Louis was married to the granddaughter of Henry II, so they invited him to take the throne of England, believing this would bring a French army to their aid.
John gave orders to gather his ships in the Thames estuary to prevent a French landing, and marched his army to Dover. On the evening of 18 May John’s luck changed. A tremendous storm came down The English Channel and smashed his ships at their moorings. Two days later, as the weather calmed, Louis sailed his army past them and landed at Thanet.
Most of John’s mercenaries were French, and they refused to fight against their Prince, so Louis was unopposed by land or sea, and won that fight without a blow being struck. Louis marched into London on 2 June, to an uproarious welcome. The rebel barons knelt and paid him homage. King Alexander II even marched all the way from Scotland to pay homage to Louis.
The pope imposed an interdict on London, but the burghers ignored it, saying he had no authority over secular matters, and mass continued to be celebrated. Four days later Louis headed out of London again in pursuit of John.
But this time fate favoured John. Louis, it turned out, was hopeless at seigecraft. Not one of the royal castles fell, except where Louis eventually managed to starve them out. In addition, the old rivalries between the French and the English were erupting all over the army. In London, the French soldiers had taken full advantage of the taverns and the brothels and generally made nuisances of themselves. In the field, the hated French were deserting every day.
Who knows what would have happened if John hadn’t fallen ill and died on 19 October 1216? He named his oldest son Henry as his heir, but the boy was only nine years old. William Marshal the Earl of Pembroke, and Hubert de Burgh were named as regents. Henry III was crowned hurriedly at Gloucester, away from Louis and his forces. 
Henry’s advisers, especially William Marshal, were well-respected men who would see to it that John’s abuses would not be continued. To that end, within a month they re-issued Magna Carta without its more objectionable clauses and vowed to see it kept. Depriving a child of his inheritance was disapproved of, and the people would much rather have an English king than one from the hated French. All these factors removed the need for civil war.
Louis was the one who lost out. His supporters streamed away and paid homage to the new king. He was forced to rely more and more on his French soldiers, which only increased his unpopularity. William Marshal was determined to remove Louis and his forces from England, and led the campaign himself, although he was over seventy. On 20 May 1217 the Earl Marshal led the attack, against a joint army of English and French, to relieve the siege of Lincoln Castle and won a decisive victory.
In September, a second French fleet carrying reinforcements was defeated, and Louis entered into peace talks. The Treaty of Lambeth was signed, in which Louis recognised Henry as king of England, acknowledged his right to the Channel Islands, promised to help him recover his father’s continental possessions and agreed never to aid Henry’s rebellious subjects. Prisoners on both sides were released and the rebel barons restored to their lands. In return William Marshal secretly paid him £7,000. Some barons objected to buying him off and wanted to continue the fight, but William Marshal wanted a quick end to the conflict.
So, had John not died when he did, England might be part of France today.