TV history sleuths have been searching the River Tees in Barnard Castle for evidence of a 16th century siege and the Roman crossing.
They have also been looking for artefacts linked to the Scottish raids along the A66.
A TV crew has been exploring the River Tees and River Greta for a programme, called River Hunters, that will air on the History Channel in next year.
Each of the eight episodes investigates a different river.
TV presenter Rick Edwards and Beau Ouimette, an underwater treasure hunter, are examining some of the most historically significant sites across Britain.
With one episode entirely devoted to Teesdale and the history of the area, they called on dale-born author Andrew Graham Stables.
Mr Stables, who wrote Secret Barnard Castle and Teesdale, was asked to offer location advice and historical support but ended up being interviewed by the presenter at both locations.
He said: “I didn’t expect to be filmed or interviewed, but after I suggested some interesting locations to the team, they asked if I would contribute and ended up filming for over three hours.”
“The crew were very professional and some shots taken with a drone I am particularly keen to see.”
They parked on the picnic area where Ullathorne Mill once stood and explored the river below the castle with metal detectors.
“This area could reveal a wealth of material from Roman time to the industrial revolution as this area is known to be the site of a Roman crossing and the industrial mills that once lined the banks of the river,” Mr Stables said.
He said the northern rebellion was a focus.
The revolt of the northern earls of 1569 was an attempt to depose the Protestant Queen Elizabeth I of England and replace her with the Catholic Mary Queen of Scots.
About 6,000 rebels, including forces from Scotland, marched in support of the earls.
They besieged and captured Barnard Castle and took the port of Hartlepool but were later defeated.
“At Bowes the main interest was the river Greta and again evidence of Roman or later Norman finds was uppermost in their minds,” said Mr Stables.
Mr Stables explained to the team how the Norman castle sat in the bounds of the Roman fort and how erosion or ploughing may have dragged artefacts down to the river since the site was occupied.
“I didn’t see Beau Ouimette as he was obviously spending most of his time in the river but Rick Edwards, who hosts the BBC quiz show Impossible, interviewed me at locations in the castle and within Bowes keep.”
The crew spent about a week in the area taking location shots, and filming the river exploration and commentary from the presentation team.
“I’m not sure what they found, but Rick kept joking that he had found a battery and a bottle top”, added Mr Stables.
“Whatever they found or the stories they uncovered about Teesdale, all will become known when the show airs in spring 2019,” said Mr Stables.
The series is covering iconic events and battles including Roman Briton, the Wars of the Roses, the Reformation and the English Civil War.
Natalie Hill, an executive producer, said: “With rivers largely unexplored in the UK, but integral to our rich past, this is a unique opportunity to find treasures long forgotten and untouched – from discarded and lost items, to offerings to gods – each river will tell a tale never seen before.”
