Irish mythology was originally a spoken tradition, but much of it was eventually written down in the Middle Ages by Christian monks, who Christianised it to some extent. Nevertheless, these tales may shed some light on what Samhain meant and how it was marked in ancient Ireland.

Irish mythology tells us that Samhain was one of the four seasonal festivals of the year. The 10th-century tale Tochmarc Emire (‘The Wooing of Emer’) lists Samhain as the first of these four ‘quarter days’. In the 12th century Serglige Con Culainn (‘Cúchulainn’s Sickbed’), it is said that the festival of the Ulaid at Samhain lasted a week: Samhain itself, and the three days before and after. They would gather on the Plain of Muirthemni where there would be meetings, games, and feasting. The tales suggest that alcohol was part of the feast, and it is noteworthy that every tale that features drunkenness is said to take place at Samhain.

According to Irish mythology, Samhain (like Beltane) was a time when the ‘doorways’ to the Otherworld opened, allowing supernatural beings and the souls of the dead to come into our world; but while Beltane was a summer festival for the living, Samhain ‘was essentially a festival for the dead’. The Boyhood Deeds of Fionn says that the sídhe (fairy mounds or portals to the Otherworld) ‘were always open at Samhain’.

Some tales may suggest that offerings or sacrifices were made at Samhain. In the Lebor Gabála Érenn (‘Book of Invasions’), each Samhain the people of Nemed had to give two-thirds of their children, their corn and their milk to the monstrous Fomorians. The Fomorians seem to represent the harmful or destructive powers of nature; personifications of chaos, darkness, death, blight and drought. This tribute paid by Nemed’s people may represent a ‘sacrifice offered at the beginning of winter, when the powers of darkness and blight are in the ascendant’. According to the later Dindsenchas and the Annals of the Four Masters, which were written by Christian monks, Samhain in ancient Ireland was associated with a god or idol called Crom Cruach. The texts claim that a first-born child would be sacrificed at the stone idol of Crom Cruach in Magh Slécht. They say that King Tigernmas, and three-fourths of his people, died while worshiping Crom Cruach one Samhain. Other texts say that kings Diarmait mac Cerbaill and Muirchertach mac Ercae both died a threefold death on Samhain, which may be linked to human sacrifice.

Many tales and events in Irish mythology happen or begin on Samhain. The invasion of Ulster that makes up the main action of the Táin Bó Cúailnge (‘Cattle Raid of Cooley’) begins on Samhain. As cattle-raiding typically was a summer activity, the invasion during this off-season surprised the Ulstermen. The Second Battle of Magh Tuireadh also begins on Samhain. The Morrígan and The Dagda meet and have sex before the battle against the Fomorians; in this way the Morrígan acts as a sovereignty figure and gives the victory to the Dagda’s people, the Tuatha Dé Danann. In the Boyhood Deeds of Fionn, Aillen burns Tara each Samhain after lulling everyone to sleep. One Samhain, the young Fionn Mac Cumhaill is able to stay awake and slays Aillen, and is made leader of the fianna. In Aislinge Óengusa (‘The Dream of Óengus’) it is when he and his bride-to-be switch from bird to human form, and in Tochmarc Étaíne (‘The Wooing of Étaín’) it is the day on which Óengus claims the kingship of Brú na Bóinne.

In the Echtra Neraí (‘The Adventure of Nera’), King Ailill of Connacht sets his retinue a test of bravery on Samhain night. He offers a prize to whomever can make it to a gallows and tie a band around a hanged man’s ankle. Each challenger is thwarted by demons or spirits and runs back to the king’s hall in fear. However, when Nera succeeds, the dead man asks for a drink. Nera carries him on his back and they stop at three houses. They are turned away from the first two. When they enter the third, the dead man drinks dirty water and spits it on the householders, killing them. Nera returns him to the gallows and then follows a fairy host through a portal into the Otherworld, where he is trapped until the next Samhain. Taking etymology into consideration, it is interesting to note that the word for summer in the Echtra Nerai is samurai.

The 14th century tale Aided Chrimthainn maic Fidaig (‘The Killing of Crimthann mac Fidaig’) tells how Mongfind tried to kill her brother Crimthann (the King of Munster) to make sure her son Brian succeeded to the throne. Mongfind offered Crimthann a poisoned drink at the Samhain feast, but he asked her to drink from it first. Having no other choice but to drink the poison, she died on Samhain eve, after which the festival came to be known as Mongfind’s or Mongfhionn’s Feast, ‘wherefore women and the rabble make petitions to her on samain-eve.’

Oweynagat (‘cave of the cats’), one of the many ‘gateways to the Otherword’ from whence beings and spirits were said to have emerged on Samhain.

Several sites in Ireland are especially linked to Samhain. Each Samhain a host of otherworldly beings was said to emerge from Oweynagat (‘cave of the cats’), at Rathcroghan, Co Roscommon. The Hill of Ward (or Tlachta) in Co Meath is thought to have been the site of a great Samhain gathering and bonfire; the Iron Age ringfort is said to have been where the goddess or druid Tlachta gave birth to triplets and where she later died.

Image | Cú Chulainn going into battle in the Táin Bó Cúailnge, which was said to have begun at Samhain