Fifty beheaded young men found in a burial pit last year were probably executed Vikings, archaeologists revealed today.
Teeth samples from 10 of the decapitated warriors discovered in Weymouth, in Dorset, show that they were Scandinavian invaders who fell into the hands of Anglo Saxons.
Dating back to between AD910 and AD1030, the mass war grave is among the largest examples ever found of executed foreigners buried in one spot.
The remains have been analysed by Dr Jane Evans and Carolyn Chenery at NERC Isotope Geosciences Laboratory, part of the British Geological Survey, based in Nottingham.
The isotopes - variations of elements - found in the men's teeth show that they grew up in countries where the climate is colder than in Britain, with one individual thought to be from north of the Arctic Circle.
The unique burial site was uncovered on Ridgeway Hill in June 2009 during an earthwork operation for a relief road.
Over the following two months, Oxford Archaeology carefully removed the 51 decapitated skulls from the ground - which were placed in one distinct area of the pit - and the bodies discarded haphazardly in another area of the pit.
It appears the men were slaughtered by local Anglo Saxons at a designated formal spot, probably in front of an audience.
At the time the Anglo Saxons were falling victim to increasing Viking raids, from a couple of ships up to invasion forces of 100 boats.
The uneasy relationship between the two groups eventually ended with the country being ruled by a Danish king.
Oxford Archaeology project manager David Score said: "The find of the burial pit on Ridgeway was remarkable and got everyone working on site really excited.
"To find out that the young men executed were Vikings is a thrilling development
"Any mass grave is a relatively rare find, but to find one on this scale, from this period of history, is extremely unusual and presents an incredible opportunity to learn more about what is happening in Dorset at this time."
Without analysing all the bodies it is impossible to know for certain that all were Vikings, but it is possible to make a "strong inference", Mr Score said.
Leader of Dorset County Council Angus Campbell said: "We have a tremendous historic environment here in Dorset but we never would have dreamed of finding a Viking war grave.
"We've had prehistoric finds from the investigation on Ridgeway before construction work started and we were thrilled by evidence of an Iron Age settlement found on Southdown Ridge during the earthworks.
"The burial pit took us all by surprise and its story gets more fascinating as the analysis goes on."
Specialists are continuing to examine the remains to try and piece together the story of the pit.
Many of the executed men suffered multiple wounds - inflicted by a sharp bladed weapon - to the skull and jaw as well as the upper spine, all thought to relate to the process of decapitation.
A scarce selection of other wounds have been found on some men, including a cut to the pelvis, blows to the chest and stomach and defensive injuries to the hands.
There are also two examples of healed fractures, which are unlikely to have been medically treated. In one case this has led to the right leg being five centimetres shorter than the left. These individuals would have both had pronounced limps.
It is hoped further evidence about the demographic make-up, lifestyles, activities, general health and diets of the warriors will come to light as the analysis continues.
The latest results show that the men had eaten a high protein based diet, comparable with known sites in Sweden, and came from a range of places in Scandinavia.
Dr Jane Evans explained: "Isotopes from drinking water and food are fixed in the enamel and dentine of teeth as the teeth are formed in early life.
"By completing a careful preparation and chemical separation process in the laboratory, the elements are extracted and their isotope composition can be measured.
"The isotope data we obtained from the burial pit teeth strongly indicate that the men executed on the Ridgeway originated from a variety of places within the Scandinavian countries.
"These results are fantastic, this is the best example we have ever seen of a group of individuals that clearly have their origins outside Britain."