The Battle of Bosworth was fought on 22nd August 1485 near Market Bosworth to the west of Leicester. Richard III, having usurped the throne from his nephew Edward V, faced Henry Tudor who claimed the throne by remote descent from John of Gaunt. Richard began with a superiority in numbers but was deserted by Lord Stanley, and the Earl of Northumberland famously stood by, watching the outcome. Richard was killed and the crown passed to Henry Tudor, King Henry VII.
Editors. "Battle of Bosworth". The Literary Encyclopedia. First published 01 January 2006
[http://www.litencyc.com/php/stopics.php?rec=true&UID=1692, accessed 20 May 2013.]