Battle of Bosworth Field - Wikipedia

On August 22 1485, the Battle of Bosworth Field took place. Henry Tudor's forces defeated English King Richard III during the last battle in the Wars of the Roses. From the article:

"The Battle of Bosworth Field (or Battle of Bosworth) was the last significant battle of the Wars of the Roses, the civil war between the Houses of Lancaster and York that extended across England in the latter half of the 15th century. Fought on 22 August 1485, the battle was won by the Lancastrians. Their leader Henry Tudor, Earl of Richmond, by his victory became the first English monarch of the Tudor dynasty. His opponent, Richard III, the last king of the House of York, was killed in the battle. Historians consider Bosworth Field to mark the end of the Plantagenet dynasty, making it a defining moment of English and Welsh history.

Richard's reign began in 1483. At the request of his brother Edward IV, Richard was acting as Lord Protector for his twelve-year-old son Edward V. Richard had Parliament declare Edward V illegitimate and ineligible for the throne, and took it for himself. Richard lost popularity when the boy and his younger brother disappeared after he incarcerated them in the Tower of London, and his support was further eroded by the popular belief that he was implicated in the death of his wife. Across the English Channel in Brittany, Henry Tudor, a descendant of the greatly diminished House of Lancaster, seized on Richard's difficulties so that he could challenge his claim to the throne. Henry's first attempt to invade England was frustrated by a storm in 1483, but on his second attempt he arrived unopposed on 7 August 1485 on the southwest coast of Wales. Marching inland, Henry gathered support as he made for London. Richard mustered his troops and intercepted Henry's army south of Market Bosworth in Leicestershire. Thomas, Lord Stanley, and Sir William Stanley brought a force to the battlefield, but held back while they decided which side it would be more advantageous to support.

Richard divided his army, which outnumbered Henry's, into three groups (or "battles"). One was assigned to the Duke of Norfolk and another to the Earl of Northumberland. Henry kept most of his force together and placed it under the command of the experienced Earl of Oxford. Richard's vanguard, commanded by Norfolk, attacked but struggled against Oxford's men, and some of Norfolk's troops fled the field. Northumberland took no action when signalled to assist his king, so Richard gambled everything on a charge across the battlefield to kill Henry and end the fight. Seeing the King's knights separated from his army, the Stanleys intervened; Sir William led his men to Henry's aid, surrounding and killing Richard. After the battle Henry was crowned king below an oak tree in nearby Stoke Golding, now a residential garden."