The impetuous queen, enraged at the failure of her mis sion, immediately mustered a formidable army, composed not only of her Connachtmen but also of allies from all parts of Ireland, wherewith to undertake the invasion of Ulster. On her side were the Ulster Chieftains who had gone into exile into Connacht after the treacherous slaughter of the sons of Usnech by King Conchobar of Ulster. Chief among them was Fergus, who, moreover, had a personal grievance against Conchobar. For, while Fergus was king of Ulster, he had courted the widow Ness and, in order to win her, promised to abdicate for the term of one year in favour of her son Conchobar. But when the term had elapsed, the youth refused to relinquish the throne, and Fergus in anger entered the service of Medb of Connacht. There he was loaded with favours, became the counsellor of the realm and, as appears from more than one allusion in the tale, the more than friend of the wife of King Ailill. The four leagued provinces of Ireland being gathered at Cruachan, the guidance of the host was entrusted to Fergus, because he was acquainted with the province of Ulster through which they were to march, and at the begin ning of winter — a point emphasized by the exponents of the sun — theory-the mighty host, including in its ranks the king and queen and some of the greatest warriors of Ireland, with the princess Finnabair as a lure, set forth on the raid into Ulster.