As we might expect, Medb was chagrined at the discovery. Now her herald macRoth had told her that Darè macFiachna, a landowner of Cualnge, a district in the territory of her former husband, possessed an even more wonderful bull than Ailill's, called Donn Cualnge, "the Brown Bull of Cualnge." So she despatched macRoth to Darè to pray for the loan of the bull.
Darè received the queen's messengers hospitably and readily granted her request, but in the course of the entertainment, one of the messengers, deep in his cups, spoke against Darè, and he, hearing this, withdrew his promise and swore that he would never hand over the Brown Bull of Cualnge.
III. The Gathering of Medb's Forces
The impetuous queen, enraged at the failure of her mission, 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 beginning 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.
They crossed the Shannon near Athlone and, marching through the province of Meath, arrived at the borders of Cualnge. Fortunately for the invaders, the expedition took place while the Ulstermen lay prostrate in their cess, or "Pains," a mysterious state of debility or torpor which was inflicted on them periodically in consequence of an ancient curse laid upon Conchobar and the warriors of Ulster as a punishment for a wrong done to the goddess Macha. This strange malady, resembling the couvade among certain savage nations, ordinarily lasted five days and four nights, but on this occasion the Ulstermen were prostrate from the beginning of November till the beginning of February. During all that time the burden of defending the province fell on the shoulders of the youthful champion Cuchulain, who had in his particular charge the plain of Murthemne, the nearest district to Cualnge, the goal of the expedition. For Cuchulain and his father Sualtaim were alone exempt from the curse and the "Pains" which had befallen the remainder of the champions of Ulster.
IV. The Youthful Exploits of Cuchulain
The Connacht host had not proceeded far when they came upon evidence of some mighty force that opposed them. In answer to the inquiries of Ailill and Medb, Fergus explains that it is Cuchulain who disputes their further advance, and, as evidence of the superhuman strength and prowess of the Ulster youth, then in the seventeenth year of his age, the Ulster exiles recount the mighty deeds he had performed in his boyhood, chief among which is the tale according to which, as eric for the killing of the hound of Culann the Smith, the boy-hero Setanta assumed the station and the name which ever after clung to him of Cuchulain, "the Hound of Culann."
V. The Single Combats of Cuchulain
Cuchulain agrees to allow the Connacht host to continue their march on condition that every day they send one of their champions to meet him in single combat. When he shall have killed his opponent, the host shall halt and pitch camp until the following morning. Medb agrees to abide by these terms. In each of the contests which ensue, the heroic youth is victorious and slays many of the most celebrated warriors on the side of Connacht. The severest of all these single combats was the one in which he had as opponent his former friend and foster-brother Ferdiad. At the end of a four days' battle, in which both adversaries exhibited astounding deeds of valour, Ferdiad fell by the hands of Cuchulain.