Up to 80 members of the group from all over the country will set up a living history tented encampment in the west ward of the castle, where excavations are still discovering fascinating evidence of the different periods of occupation of the site. The re-enactors will demonstrate a variety of craft-working skills and aspects of everyday life of the period.
Throughout the weekend warriors will be practicing their weapons skills on the field in the village at the foot of the castle hill and each day's programme will end with a dramatic skirmish between the Northumbrians and a Viking raiding band.
The event celebrates the Feast of St Oswald (August 5), the 7th century King of Northumbria who established Christianity in the region.
It is one of the largest events being staged as part of this year's Golden Age of Northumbria Festival. The Golden Age project is supported by the Heritage Lottery Fund.
The King Oswald's Fortress event is open from 11am to 4.30pm on Saturday and Sunday. Admission to the living history encampment and event sites is free of charge.
Entry to the castle interior is by ticket, available from the office and the entrance as normal (£7 adult, £6 senior, £3 child).
Visitors and local people alike are also invited to join two themed guided walks covering parts of the St. Oswald's Way long distance route.
Further details of the event can be found at www.goldenageofnorthumbria.com