Very little is truly known of the ancient Celts who left no written records. The names of many of the gods worshipped by them are known through Latin or Gallo-Latin inscriptions made in late pre-Roman and Roman times.
The rituals with which these gods were celebrated have long since been forgotten. Likewise, the druids, who were the "priests" of Celtic society, have been obscured by the passage of time and the secretive nature of their order.
However one major question has remained Did the Celts practise human sacrifice?
It seems they did.
An expert has stated that the latest bog bodies found in Ireland has proven that belief that the Celts ritually sacrificed their kings to the Gods.
The body also proves they underwent horrible deaths, if the times turned bad under their reign.
The latest Iron Age bog body dating back to at least 2,000 BC was discovered near Portlaoise in the Irish midlands by an alert bog worker and it bears the same hallmarks of ritual torture that two other famous bodies have.
Ned Kelly, keeper of antiquities at the National Museum of Ireland told the Irish Examiner that a clear pattern has emerged in each case.
"We do not think of these bog bodies in the same way as we do axes or implements that are found," he says. "You have to remember that these are individuals and it is absolutely essential to deal with their remains in a dignified manner. There would be no justification in taking these bodies unless we do so with respect and with the serious intent to tell their stories on their behalf."
"I am quite convinced we are dealing with an Iron Age male, one who was subjected to a ritual killing. There are cuts and marks on the body that indicate that this is somebody who was done to death."
The body is linked closely to two other major finds, the discoveries of Old Croghan Man and Clonycavan Man, also found in Irish bogs both of whom were ritually sacrificed.
Human sacrifice was apparently a normal part of the Celtic rituals , especially of kings in hard times.
"The killings tend to be excessive," Kelly, said "in that more is done to the bodies than would be required to bring about their deaths. Bog bodies may have their throats cut, been stabbed in the heart and have other cut marks. However, it is absolutely not torture, but a form of ritual sacrifice."
"The king had great power but also great responsibility to ensure the prosperity of his people. Through his marriage on his inauguration to the goddess of the land, he was meant to guarantee her benevolence. He had to ensure the land was productive, so if the weather turned bad, or there was plague, cattle disease or losses in war, he was held personally responsible."
At 6’6", Old Croghan Man, who was killed between 362 BC and 175 BC, was a giant of a man. he bore every appearance of a nobleman from his well manicured soft hands to his diet, which was rich in meat.
Clonycavan Man was little more than 5 ft and used pine resin to keep his hair in place.
Kelly says Old Croghan Man died horribly, had had holes cut in his upper arms through which a rope was pulled through in order to restrain him. He was stabbed repeatedly and he had his nipples sliced, before he was finally cut in half.
Clonycavan Man was disemboweled and struck three times across the head with an axe and once across the body and also had his nipples cut.
Cutting the nipples was more than torture, the aim was to dethrone the king. "Sucking a king’s nipples was a gesture of submission in ancient Ireland," says Kelly. "Cutting them would have made him incapable of kingship in this world or the next."
"By using a range of methods to kill the victim, the ancient Irish sacrificed to the goddess in all her forms. This manner of death is peculiar to the ritual killing of kings. It means that a king was being decommissioned."
"I think it is important we treat them with respect. They have come down to us with a story to tell and it is our duty to tell that story on their behalf. If we do that, it will give added meaning to their lives."
In all of Ireland's rich and ancient mythical tradition - there is only one reference to human sacrifice. The High King of Teamhair, Tigernmas, set up an idol called Cromm Cruach, and ordered that children be killed as offerings to it. It was, ironically, the druids of Ireland that brought an end to this bloody cult, murdering Tigernmas during a frenzied ceremony around the idol.
Elsewhere in Europe It does appear that the Celts performed human sacrifice as part of their religious rituals. Since the Druids were the religious social class, they almost certainly would have participated in human sacrifices, and probably officiated at them.
This adds weight to theories and accounts from ancient Rome of Druidic killing, archeologists have said.
Experts say that Druids in the Celtic era possibly committed ritual human sacrifice on a mass scale. Julius Caesar, who led the first Roman landing in 55 BC, said the native Celts ‘believed that gods delighted in the slaughter of prisoners and criminals, and when the supply of captives ran short, they sacrificed even the innocent.’