November 1st was traditionally known as samhain, literally translated the "end of summer" and pronounced something like sow-een. This was the end of the Celtic year, the start of winter, a time for reflection. And part of a sometimes confusing tradition ...
From Darkness Comes Light
One of the Celtic idiosyncrasies was the concept of beginning in darkness and working towards the light. As the year started with winter, the days started at sundown. Thus the night from October 31st to November 1st was part of samhain, known as oiche shamhna or "evening of samhain".
Samhain was one of the four "quarter days" of the Celtic calendar, along with imbolc (February 1st, start of spring), beltane (May 1st, start of summer) and lughnasa (August 1st, start of the harvest). We do not have any undisputed information about how these festivities were conducted in pre-Christian times. Samhain seems to have been a specifically Irish tradition and first mentioned by Christian chroniclers. Feasting seems to have taken the best part of a week, a few days either side of the actual samhain day.
Samhain - Preparing for Winter
The preparations concerned mainly cattle and other livestock - all members of the herd were caught, brought into enclosures or sheds near the homestead. And some were marked for death - those animals too weak to survive the winter were slaughtered. Not for any ritual reasons, this was down to purely practical considerations. And filled the larder for winter.
At the same time all corn, fruits and berries had to be harvested and stored. There still is a widespread belief in Ireland that after November 1st all fruit is bewitched and thus inedible. The pooka was said to roam free at samhain - a black, ugly horse with red eyes and the ability to talk. And with a penchant for kidnappings and copious urination on berries. On the other hand a respectful contact with the pooka could show you the future ...
Communal Activities - Samhain as a Day of Reckoning
Many legends concern the big meetings at samhain - this was the time to take stock and decide upon future activities. At the Hill of Tara or on lakeshores. A general armistice during this period made meetings between sworn enemies, diplomacy and social activities beyond tribal and political boundaries possible. All debts had to be settled and horse-racing as well as charioteering provided a peaceful contest.
But spiritual activities were an integral part of the feast.
Traditionally all the fires were extinguished when oiche shamhna set in, making this the darkest night of the year. The fires were then re-lit, marking the start of the new year.
Tradition has it that druids lit a huge bonfire on the Hill of Tlachtga (near Athboy, County Meath) and burning torches were then carried from there to every household during the night - alas, a physical impossibility. Though the reputed special tax levied by the king for this "service" certainly seems believable in light of the modern Irish state's revenue ideas ...
We All Have to Make Sacrifices
Other rituals involving fire were not so quaint and definitely easier to arrange - the "wicker men". Basically a cage made from wickerwork in a rough resemblance of the human form, then stuffed with (living) sacrificial offerings. Like animals, prisoners of war or unpopular neighbors. Which were then burned to death inside the "wicker man". Other rituals involved drowning ... Happy New Celtic Year!
But these human sacrifices should not be seen as the undisputed norm. Though sacrifices were undoubtedly made, they may only have involved milk and corn spilled into the earth. And there might even have been nocturnal human activities connected to fertility rituals. It was considered a good omen if a woman became pregnant at samhain!
The Non-Human Touch at Samhain
Not everybody joining in the samhain celebrations was necessarily human ... or of our world. The night from October 31st to November 1st was a time "between years" to the Celts. And during this time the borders between our world and the otherworld(s) were flexible and open.
Not only the pooka was out and about ... bean sidhe (banshee) could be killed by humans during the night, fairies were visible to human eyes, the underworld palaces of the "gentry" (an Irish title for fairies) were open to come and go. Humans could drink with mighty heroes and bed their beautiful female companions ... as long as you did not make any mistakes, broke any rules or violated even the most ridiculous taboo. The problem being that the chances to foul up far outweighed the chances of a good night out - so most people opted for a quiet night in. Doors securely locked.
Last but not least Uncle Brendan might come knocking, even though he has been buried the last twenty years in New York. Samhain was also a time when the dead could walk the earth, communicate with the living ... and call in old debts.
All this belongs to the conservative picture of samhain. Which has been thoroughly muddled by neo-pagans and esoteric authors detailing "lost knowledge". To such a degree that even a Celtic god of death called samhain appeared - a pure invention.
Colonel Charles Valency is to blame for many inventions. In the 1770s he wrote exhaustive treatises on the origin of the "Irish race" in Armenia. Many of his writings have long been consigned to the lunatic fringe. But Lady Jane Francesca Wilde carried his torch in the 19th century and her "Irish Cures, Mystic Charms and Superstitions" - which is still being cited as an authoritative work.
Samhain meanwhile mutated into All Hallows E'en and Halloween. And samhain or Halloween is still celebrated in Ireland in various ways - complete with fortune telling and special meals.