 Complete the following phrase:  Hostilities between the rival Yorkist and Lancastrian factions soon flared into armed conflict. In May 1455, just over five months after Henry VI recovered from a bout of mental illness and Richard of Yorks protectorship had ended, Margaret called for a Great Council from which the Yorkists were excluded. The Council called for an assemblage of the peers at Leicester to protect the king against his enemies. York apparently was prepared for conflict and soon was marching south to meet the Lancastrian army marching north. The Lancastrians suffered a crushing defeat at the 