William Marshal served four successive English kings, from Henry II through Richard I, John, and Henry III, and became known as the greatest knight of the Middle Ages.
Marshal was born around 1146 and entered aristocratic service as a younger son with limited inheritance. His reputation grew through tournaments, military campaigns, and loyal service. He became guardian of the young Henry III after King John died in 1216.
William also helped secure the succession during the First Barons' War. As regent, he defeated the rebel barons and their French allies at the Battle of Lincoln in 1217. His career illustrates how martial skill, political loyalty, and tournament prestige could raise a landless younger son to the highest ranks.
The medieval chronicler John of Earley recorded Marshal's life in detail, making him one of the best-documented knights of the period. Modern historians sometimes qualify the phrase “greatest knight” because it comes from later descriptions, but Marshal's four royal connections and military career are firmly established.