The rebel barons were coming to terms with the fact they lived in a lawless country where even though they owned land and had titles, the king could still do whatever he wanted to them.
What they needed was a list of rights, something that clearly stated that, before the king could carry off their belongings and give their lands to someone else, they deserved a trial with witnesses and a jury.
And that's just what the Magna Carta did.
The rebel barons were whiney babies complaining about lacking rights when they had castles (literally castles) to go home to. The people who actually needed a list of rights were the serfs who were practically enslaved and lacked even the most basic human necessities.
The amazing thing about the rights demanded in the Magna Carta is that they remain fundamental rights asked for by all people hundreds of years later, making it a document of universal appeal.
A lot of the Magna Carta takes outrage that would have been expressed as, "How dare you sir! I will not stand for this injustice!" and translates it into formal sounding legalese.
For each clause that explains some offense, you just know that there was some red-faced baron with steam coming out of his ears. These barons were willing to stand up to a king with absolute authority and explain to him how unfair he was being. It's a safe bet that they were pretty angry.
King John of England embodied injustice in both his personal and professional life. With every new revelation about his doings a more shocking wrong is revealed.
King John's failure wasn't that he was unjust, merely that he was a politician working in a system that did not yet value fairness.
In some ways the rebel barons weren't really asking for much. They lived at a time when there were already plenty of dumb rules that ruined everything. Their lives were filled with inexplicable taxes (why should you have to pay the king so that your daughter can get married?) and traditional ways of doing things that nobody was allowed to question.
All they were saying in the Magna Carta was that King John should stick with the terrible rules already in place and not make up new terrible rules. Because King John wasn't just being unfair; he was being unfair in a wholly unfamiliar way.
King John was an innovator ahead of his time. If he had lived in a time and place where change was more easily accepted he might have been respected for his cleaver manipulation of the tax code.
The barons were really rebelling against all of England's many harmful traditions and customs. They were just starting with those most closely associated with the hated King John. If they'd been more successful the takedown of other traditions would have surely followed.
It isn't pleasant, but the reality of life in the medieval era was that people often died young and they often died suddenly. And as if that isn't grim enough, those deaths would open up a whole mess of ways for people to abuse and steal from the dead person's family.
The king was, of course, in the absolute best position for rampant death-related thievery because he could disguise it by calling it a tax. The Magna Carta has the job of trying to close some of these loopholes and regulate the way that medieval people dealt with frequent mortality.
By unfairly exploiting the families and children of deceased parents, King John crossed the line from merely greedy and unpopular to that of a monster and thus brought the baron's revolt on himself.
Don't blame King John for the horrors of the feudal system. That system made dealing with underage heirs without any fair process a reality.
The Magna Carta is an odd sort of peace treaty—it came before a war and not after one.
It was designed to stop the king and the barons from fighting and therefore it doesn't declare a winner or a loser, but it's obvious that the barons are the ones demanding things and the king is the one forced to comply.
The document is one sided, with the king all but admitting defeat in numerous places and with multiple capitulations to his nobles and the church. Of course, to him this was all a ruse that he didn't really mean and that wouldn't prevent a war from taking place.
King John may have come across as a loser because he gave in to so many demands in the Magna Carta, but by giving up so much he made it plausible that he was being forced and therefore came out a winner when the pope nullified it for him.
The Magna Carta is the greatest defeat for monarchies in the history of the world. It's not only a defeat of John's crown, but it leads to the defeat of the divine right of kings and has played a role in every deposed royal since 1215.
If the government did something to hurt you in the medieval era, your options were limited.
Courts of law had been invented, but they were only sporadically used and you couldn't sue—let alone complain about—the government. Basically, your only option (other than doing nothing) was to grab a sword and try to lead a rebellion, which would almost certainly result in the death of you and your whole family.
Basically, the Magna Carta attempted to bring some rules into a society hungry for some order and discipline.
The twenty-five barons would have certainly been a marauding force bent on drunkenly pillaging the king's property.
If the council of barons had come into reality shortly after the Magna Carta, it would have revolutionized the world and brought an enviable stability to England where the people would have basked in the many benefits of rules and order.