It might sound a whole lot like Disney's animated Robin Hood, but life under King John in the 1200s wasn't really worth singing about.

For many years, King John ruled England absolutely and arbitrarily because he was king and could do that. When he lost a bunch of land to France, King John raised taxes to pay for a war to get that land back. However, it failed (pretty spectacularly as those things tend to do), and King John needed even more money to end the conflict.

But the English barons had had enough and refused to pay the increasingly high taxes. Instead, they threatened to go to war with the king unless John agreed to sign the Magna Carta, a document that guaranteed them certain rights and limited the king's power.

You can bet John wasn't too crazy about doing that.

Unfortunately for him, there really wasn't much choice. Civil war broke out, and the rebels eventually gained control of London. The Magna Carta was intended to serve as a peace treaty but had to be reissued multiple times to avoid further conflict.

That said, the legacy of the document is what's most important. It's the first constitution in European history, and even though many of the benefits remained reserved for the upper class well into the 17th century, the Magna Carta served as inspiration for the American colonists as they drafted the Declaration of Independence.