Excerpts from Books and Wikipedia
"The Wars of the Roses were a series of English civil wars for control of the throne of England fought between supporters of two rival cadet branches of the royal House of Plantagenet: the House of Lancaster, associated with the Red Rose of Lancaster, and the House of York, whose symbol was the White Rose of York. Eventually, the wars eliminated the male lines of both families. The conflict lasted through many sporadic episodes between 1455 and 1487, but there was related fighting before and after this period between the parties. The power struggle ignited around social and financial troubles following the Hundred Years' War, unfolding the structural problems of bastard feudalism, combined with the mental infirmity and weak rule of King Henry VI which revived interest in the House of York's claim to the throne by Richard of York. Historians disagree on which of these factors to identify as the main reason for the wars." [Wikipedia] The Battle of St. Albans occurred in 1455. "Traditionally marks the beginning of the War of the Roses." [Wikipedia: Timeline of Middle Ages]