Why do you think john agreed to sign the charter (magna carta)?

Here the barons demanded that King John sign a document called the Magna Carta guaranteeing them certain rights. By signing the document, King John agreed to do his duty as King of England, upholding the law and running a fair government. In return, the barons agreed to stand down and surrender London.

after the french-indian war.

this is a good question! i'll do some research and come back when i have the answer!