Many castles, especially royal castles, were left to decay in the 15th century; Kenilworth, however, continued to be used as a centre of choice, forming a late medieval "palace fortress".[88] Henry IV, John of Gaunt's son, returned Kenilworth to royal ownership when he took the throne in 1399 and made extensive use of the castle.[2] Henry V also used Kenilworth extensively, but preferred to stay in the Pleasance, the mock castle he had built on the other side of the Great Mere.[52] According to the contemporary chronicler John Strecche, who lived at the neighbouring Kenilworth Priory, the French openly mocked Henry in 1414 by sending him a gift of tennis balls at Kenilworth.[89] The French aim was to imply a lack of martial prowess; according to Strecche, the gift spurred Henry's decision to fight the Agincourt campaign. The account was used by Shakespeare as the basis for a scene in his play Henry V.[89]