Individual Details

He was an illegitimate son of Henry II of England. His mother was unknown for many years, until the discovery of a charter of William mentioning "Comitissa Ida, mater mea" (engl. "Countess Ida, my mother").

Ida de Tony, possibly a member of the prominent Tony or Touny family, later married Roger Bigod, 2nd Earl of Norfolk.

King Henry acknowledged William as his son and gave him the Honour of Appleby, Lincolnshire in 1188. Eight years later, his half-brother, King Richard I, married him to a great heiress, Ela of Salisbury, 3rd Countess of Salisbury in her own right, and daughter of William of Salisbury, 2nd Earl of Salisbury. William and Ela had four sons and six daughters.

During the reign of King John, Salisbury was at court on several important ceremonial occasions, and held various offices: sheriff of Wiltshire, lieutenant of Gascony, constable of Dover and warden of the Cinque Ports, and later warden of the Welsh Marches. He was then, circa 1213, appointed sheriff of Cambridgeshire and Huntingdonshire.

In 1214, as Marshal of the King, commanded forces which recovered nearly all of Flanders for the Count of Flanders; however, he and the Count were captured at the Battle of Bouvines and thrown into prison. He was release before May of 1215 and returned to England. In 1215 he was present at Runnymeade, on the king's side, at the signing of the Magna Carta.

He died at Salisbury Castle. Roger of Wendover alleged that he was poisoned by Hubert de Burgh. He was buried at Salisbury Cathedral in Salisbury, Wiltshire, England.

Birth	Bet 1175 and 1180
Marriage	Bef Sep 1197	Ela of Salisbury
Death	7 Mar 1225/26	Salisbury Castle, England

Spouse	Ela of Salisbury ( - 1261)
Child	Ida Longespee ( - 1270)

Father	Henry Plantagenent II, King of England (1154-1189) ( - 1189)
Mother	Ida de Tosny ( - 1185)