The Barons' War: Second Edition – Core Rulebook

From BoardGameGeek:

In the Kingdom of England by 1215, a group of powerful barons had reached breaking point due to King Johns despotic rule, high taxes and failed leadership. It was time to rebel! Written by Andy Hobday, these rules enable narrative-driven tabletop games set in an England gripped by civil war played out against the backdrop of the Magna Carta and the invasion by the Crown Prince of France. The historically themed gameplay is fast-paced and tactical. With warriors of this period being pretty similar, it is easy to base your medieval skirmish games using these rules in any setting. This softback rulebook contains 138 pages (with original wraparound cover art by Peter Dennis) which include the rules (of course), retinue lists, a quick reference sheet (with page numbers), a glossary and an index! -description from the publisher