Aubrey IV was supposedly an ally of King John, while his brother Robert, the 3rd Earl was one of the 25 barons of Magna Carta. His descendant, another Robert, the 9th Earl, was a favourite of King Richard II who created him Duke of Ireland. John the 13th Earl was a Lancastrian during the War of the Roses and Henry Tudor's commander at the Battle of Bosworth Field in 1485. The 17th Earl has become the most famous of the line because of his emergence as a popular alternative candidate as the actual author of the works of William Shakespeare (see Oxfordian theory of Shakespeare authorship). The 17th Earl was a ward and later son-in-law of Lord Burghley, Queen Elizabeth I's Secretary of State. On the death of the 20th Earl, without identifiable heirs male, the title became dormant.