Question: How long did the War of the Roses last where Henry Beaufort was an important Lancastrian military commander?

<P0-S0>  The conflict lasted through many sporadic episodes between 1455 and 1487; however, there was fighting before and after this period between the houses. <P0-S1>  The power struggle ignited around social and financial troubles following the Hundred Years' War, combined with the mental infirmity and weak rule of Henry VI which revived interest in Richard of York's claim to the throne. <P0-S2>  Historians disagree about whether the Wars of the Roses were caused by the structural problems of feudalism or Henry VI's ineffectiveness as king. <P0-S3> The Wars of the Roses were a series of wars for control of the throne of England fought between supporters of two rival branches of the royal House of Plantagenet: the House of Lancaster (associated with a red rose), and the House of York (whose symbol was a white rose). <SEP> <P1-S0> John Clifford, 9th Baron Clifford, (8 April 1435 – 28 March 1461), was a Lancastrian military leader during the Wars of the Roses. <P1-S1>  The Clifford family were one of the most prominent families among the northern English nobility of the fifteenth century; and by the marriages of his sisters John Clifford had links to some very important families of the time, including the earls of Devon. <P1-S2>  He was orphaned at about twenty years of age when his father was slain at the first battle of the Wars of the Roses, the Battle of St Albans in 1455. <P1-S3>  It was probably as a result of his father's death there that John became one of the strongest supporters of Queen Margaret of Anjou, consort of King Henry VI, who ended up as effective leader of the Lancastrian faction. <P1-S4>  John Clifford had already achieved prominence in the north where, as an ally of the son of the earl of Northumberland, he took part in a feud against the Neville family, the Percy's natural rivals in Yorkshire. <P1-S5>  This consisted of a series of armed raids, assaults and skirmishes, and included an ambush on one of the younger Nevilles' wedding party in 1453. <P1-S6>  Historians have seen a direct connection between his involvement in the local feud in the north with the Nevilles, and his involvement in the national struggle against the duke of York, whom the Nevilles were closely allied with in the late 1450s. <P1-S7>  Although this was supposedly a period of temporary peace between the factions, Clifford and his allies appear to have made numerous attempts to ambush the Neville and Yorkist lords. <SEP> <P2-S0> Humphrey Stafford, 1st Duke of Buckingham, 6th Earl of Stafford, {'1': ", '2': ", '3': ", '4': "} (15 August 1402 – 10 July 1460) was an English nobleman and a military commander in both the Hundred Years' War and in the Wars of the Roses. <P2-S1>  A great-grandson of King Edward III on his mother's side, he inherited his father's earldom of Stafford at an early age. <P2-S2>  Through his marriage to a daughter of Ralph, Earl of Westmorland, Humphrey was not only related to the powerful Neville family, but many of the leading aristocratic houses of the time. <P2-S3>  Like his father, he joined the English campaign in France and fought for King Henry V; on the King's death he became a leading councillor for the new King, the six-month old Henry VI. <P2-S4>  He acted in a peace-making role in the partisan politics of the 1430s, when Humphrey, Duke of Gloucester vied with Cardinal Beaufort for political supremacy, and he was also involved in the arrest of the duke in 1445. <SEP> <P3-S0>  He is sometimes numbered the 2nd Duke of Somerset, because the title was re-created for his father after his uncle died. <P3-S1> Henry Beaufort, 3rd Duke of Somerset (26 January 1436 – 15 May 1464) was an important Lancastrian military commander during the English Wars of the Roses. <P3-S2>  He also held the subsidiary titles of 5th Earl of Somerset, 2nd Marquess of Dorset and 2nd Earl of Dorset.