By a not unheard-of publishing coincidence, this brilliant and controversial volume in the ""Crossroads of World History"" series, a study of the 15th-century wars for the English throne between the houses of Lancaster and York, appears within four days of a similar book on the same subject, J.R. Lander's Wars of the Roses (p. 294). Lander tells the story through excerpts from contemporary documents, using the same sources, and also Shakespeare's historical plays; Rowse, an authority on Tudor England, interprets the complicated tale in his own terms. The century-long struggle had its inception in 1399, when Henry IV of Lancaster seized the throne from Richard II of York. It ended in August, 1485, when Richard III, brother of the dead King Edward IV of York, rode with his army to Bosworth, a gold crown over his helmet, to fight the last Lancastrian heir, Henry Tudor. Deserted by his own men, Richard was killed in the battle; his crown, found in the field, was placed on the head of the first Tudor king, Henry VII, who united the warring houses by marrying Edward IV's daughter. ""Enjoyable for the fighting type,"" the struggle was ""a confounded nuisance for the solid citizen."" It is also a confounded nuisance for today's amateur historians, lost in a fog of turbulence that not even Rowse's skill can completely disperse. Wars spilled across the Channel and back again, English kings claimed the French throne, families were decimated, kings murdered, dukes beheaded. Edward IV put to death the weak and beloved Henry VI; Edward's two sons, ""The Princes in the Tower, "" were murdered by Richard III, his own brother. They were a fine lot, and out of the ruckus they raised emerged modern England.