Three of William Ros's children fought in the last period of the Hundred Years' War. John, his heir, was born in 1397 and was legally a minor when Ros died. The Earl of Dorset, the king's cousin, received custody of the Ros estates. Before he inherited, John travelled to France with the new king in 1415 and fought at the Battle of Agincourt at the age of seventeen or eighteen. He died in 1421 at the Battle of Baugé with the king's brother, Thomas, Duke of Clarence and Sir Gilbert V de Umfraville. William Ros's second son Thomas was only fourteen at John's death, and fought with Thomas, Earl of Salisbury, at the siege of Orléans in 1428; he died after a skirmish outside Paris two years later. Thomas' heir (also named Thomas) inherited the lordship as 9th baron and played an important role in the Wars of the Roses fighting for the Lancastrian king, Henry VI; he was beheaded after his defeat by the Yorkists at the Battle of Hedgeley Moor in 1464. Ros's wife, Margaret Fitzalan, lived until 1438. She had received her dower by February 1415 and, at the marriage of Henry V to Catherine of Valois in 1420, entered the new queen's service as a lady-in-waiting. Margaret attended Katherine's coronation and travelled with her to see Henry in France two years later.