Is it ensure, insure, or assure?
A series of wars fought by two English houses, or families, in the late fifteenth century for rule of the country. The House of Lancaster had a red rose as its emblem; the House of York had a white rose. The forces of the House of Lancaster won, and their leader, Henry Tudor, father of the future King Henry VIII, became king. The power of the English kings was strengthened in the period that followed.