In Irish myths, the fictional history of Ireland can be divided into three periods. The Mythological Cycle or the Book of Invasions, comprised of successive settlements of early Celtic people on Ireland, particularly the Tuatha Dé Danann and the Milesians.The other two cycles were supposed to be set at a later time. The Ulaid Cycle deal with the reigns of Conchobor of Ulaid and Medb of Connacht, particularly the warriors of the Red Branch and its greatest hero, Cuchulainn. The Fenian Cycle, supposed to have been set in a more peaceful time of the reign of Cormac the Airt, particularly the warriors of Fianna and its greatest hero, Finn Mac Cumhaill.

According to the Book of Invasions, translated by the Catholic Monks in medieval times, Cesair, daughter of Bith and granddaughter of Noah, was the leader of the first invasion in Ireland. She was denied admission to the Ark, so she left 40 days before the Flood arrived with 50 other women, and three men. The three men were to divide the women among them and were expected to populate the land. Unfortunatley, two of the men died. When the fifty women all turned their attention to Fintan, he saw that they were placing too much responsibility to him, so he fled from Ireland, by turning himself into a salmon. Cesair died from a broken heart. Without a single man on the isle, the other women also perished.

The Partholanians were the second group of Celtic people who settled in Ireland, the first to arrive after the biblical Flood. Their leader, one Partholan, had fled from Greece, after murdering his own father and mother. Accompanied with his wife Dealgnaid and a group of followers, they reached Ireland, after wandering for seven years.However, Partholon died 30 years after his arrival. The rest of the Partholonians died 120 years later from pestilence. The only survivor of the plague was Tuan, a nephew of Partholon.

Tuan witnessed the arrival of Nemed and his followers, known as the Nemedians, thirty years after the last Partholonian, not counting Tuan. Tuan kept himself hidden from the Nemedians. When Nemedians were gone from Ireland, Tuan still lived, for many generations. Tuan survived because he was transformed into various animal shapes. First as a stag, then as a boar and later as an eagle. In each form, he witnessed successive early invaders of Ireland. When he was transformed into a salmon, he was caught one-day, and eaten by the wife of Cairill, who immediately fell pregnant as the result of her meal. She gave birth to a son, who was named Tuan mac Cairill. It was this reborn Tuan, who was said to have written a book about the early history of Ireland.

The Fomorians were a race of strange beings, probably nothing more than pirates or raiders, since they never settled in Ireland, and never considered to be Celtic people (Irish). They were ugly, misshapen giants, who were cruel, violent and oppressive. They came into conflict with many of the early Irish settlers.

The next group to arrive in Ireland was the Firbolgs, who were actually descendants of the Nemedians, who fled Ireland from both the war against the Fomorians and the plague that ravaged their population. Semion, great-great-grandson of Nemed had brought his followers to Greece, where unfortunately they suffered from slavery and oppression at the hands of their Greek masters.

The next people to arrive in Erin (Ireland), was the Tuatha Dé Danann or the Children of the goddess Danu, under the leadership of Nuad, son of the goddess. They would later be regarded as Celtic deities by the pagan Irish, and as fairies to the Christians. Like the Firbolgs, they were descedants of Nemedians. The Danann were learned in all sorts of arts and crafts, philosophy and medicine, music and warfare, science and magic. They were scholars, bards, druids, craftsmen, and warriors. They won the First Battle of Moytura against the Firbolgs, because of their technologically superior weapons and magic. At first, the Fomorians were their allies, but later became their deadly enemies. Under the leadership of Lugh, the Dananns also defeated the Fomorians in the Second Battle of Moytura.

Ireland enjoyed a long period of peace and prosperity. Lugh Lamfada seemed to rule the Tuatha Dé Danann, after the battle and Nuada’s death.

After the Milesians defeated the Dananns, the Dananns either retreated to the Land of Youth or they continued to lived on the land with the Milesians, but their homes (subterranean palaces) were hidden by magic from the eyes of mortals. Their homes were commonly called Sidhe or the Otherworld. In the Otherworld, the Danann remained young and seemingly immortal. Immortal in the sense, they can live a very long life and remain young, but they can be killed and destroyed, just like any mortal. There were frequent visits of the Dananns with the mortals. Sometimes they aided mortals, while other times they seek their destruction. Sometimes they sought marriage with mortals. Most of the times, the Dananns would come to the surface and meet their lovers, other times the mortals were allowed to live with them.

In the Ulster Cycle, the Tuatha Dé Danann was still seen as Celtic deities. However, in the Fenian Cycle, the Dananns had degenerated into nothing more then fey people; in another words, the Dananns became the “Fairy People”.

Cuchulainn, the greatest of Celtic heroes of the Ulster Cycle endowed with superhuman qualities, was the son of Lugh, the sun god, leader of the Danann. His name means ‘The Hound of Culainn’, but he was first called Setanta.

At the age of five he left home to join the Red Branch Knights, the Ulster army of the king Conor Mac Nessa. With him he took his hurley, his silver ball, his javelin and his spear. He would hit the silver ball with the hurley, leap forward and hit it a second time before it touched the ground, toss the javelin ahead and then the spear, run after them all, catch the ball and javelin with one hand and the spear with the other.

Cuchulainn achieved his name at the age of seven when he killed the watch dog of Ulster belonging to Culainn’, the smith and in return undertook to protect the kingdom of Ulster and its people himself. Cuchulainn became the leader of the Red Branch Knights.

In battle, he was transformed by a ‘Battle Fury’ which looked like this: From head to toe, his whole body trembled like a bullrush in a river torrent. His body turned right around inside his skin so that his heels, calves and hams appeared in front. One of his eyes drew right back in his head, the other stood out huge and red on his cheek. His mouth was distorted, twisted up to his ears so you could see his throat and a man’s head would fit into it. His hair stood up on his head like hawthorn, and there was a drop of blood on every single hair. The light of the Champion stood out of his forehead as long and thick as a warrior’s whetstone and from the top of his head rose a thick column of dark blood like the mast of a huge ship. When this happened the only way he could be calmed down was by being dunked three times in cold water.

During his lifetime he made a number of enemies, and one of these Queen Maeve of Connaught brought about his downfall. The Queen learnt of a great Brown Bull in Cooley, County Louth. The chieftan of Louth refused to let Maeve have his bull, so she resolved to get it by force. Secretly she promised her beautiful daughter in marriage to every leader in her army and so secured the help of every warrior outside Ulster. The army marched to Kells, on the Ulster border and pitched camp. Maeve sought an interview with the Ulsterman and, amazed to find him a mere boy, offered him gold and great rewards if he would desist. Cuchulainn refused, but Maeve secured his agreement to fight one of her heroes each day at the ford that lay between, reckoning that this was better than losing one hundred every night to Cuchulainn’s sling.

Day after day Cuchulainn fought Maeve’s warriors, overcoming Morrigu, the water goddess, during his fight with the hero Loich who he still managed to wound mortally. After more such combats and deceitful ploys by Maeve, Cuchulainn mounted his war chariot and hurled himself against the men of Erin. Maeve with her forces sorely depleted, resorted once again to single combat. She finally forced Cúchulainn’s foster brother Ferdia to face the Ulsterman, by threatening him with the spells of her Druids. After a great fight in which Ferdia almost proved almost a match for him, Cuchulainn badly wounded, emerged as the tragic victor. While he recoverd from his wounds, the men of Ulster began to collect themselves, and the two armies faced each other on the plains of Meath. While this great battle was raging Maeve managed to capture the Brown Bull of Cooley, which she sent back to Connaught under escort. Eventually, through the intervention of Cuchulainn the Ulster army defeated Maeve’s followers and they fled back to Cruachan, from whence they had originally set out.

Cuchulainn lived on after his incredible feats of prowess, but not for long. Maeve, having bided her time, once again brought an army together to seek revenge. She had no trouble in assembling a a great number of warriors because there was scarcely one who had not a relative slain by the Ulster hero. But it was only by magic that Cuchulainn was eventually pierced by his own spear. With great difficlulty, holding in his entrails, Cuchulainn tied himself to a high stone by a lake, because as a Gaelic hero ‘he did not wish to die either sitting or lying: it was standing that he wished to meet his death’. His faithful horse protected him as he died, and it was only when a raven alighted on his shoulder that his enemies knew he was dead.

The image of Cúchulainn is invoked by both Irish nationalists and Ulster unionists, in murals, poetry, literature and other art forms. Irish nationalists see him as the most important Celtic Irish hero, and thus he is important to their whole culture. A sculpture of the dying Cúchulainn by Oliver Sheppard stands in the Dublin GPO in commemoration of the Easter Rising of 1916. By contrast, unionists see him as an Ulsterman defending the province from enemies to the south: for example, a mural on the Newtownards Road in East Belfast, ironically based on the Sheppard sculpture, depicts him as a “defender of Ulster from Irish attacks”.