A pair of identical 18th century cannons at Etal Castle are at the centre of a conservation appeal launched by English Heritage.
The nine-pounder cannons are said to have been salvaged from the HMS Royal George, an English ship that sank in 1782 with at least 800 men, women and children losing their lives.
These cannons, which could fire solid iron balls distances of up to 1,600metres, have flaking paint and small areas of corrosion which, left untreated, can thin the metal and weaken the structure.
They are sitting on replica wooden carriages, and exposure to the elements is also causing these to rot.
To save them, English Heritage needs to remove them from their carriages, remove old paint and corrosion and repaint the metal with protective paint.
The charity, which cares for more than 400 cannons, carriages and historic guns, has launched an appeal to help tackle urgent repairs to the Etal cannons, along with two more at Dover Castle and Pendennis Castle in Cornwall.
Senior collections conservator, Bethan Stanley, said: “Our cannons are precious objects, vital alongside our castles and fortifications in telling the story of England as an island nation.
“To many, they are an integral part of the landscape, but unless we act now, they could ultimately be lost to the elements.”
English Heritage also recently conserved an 18-pounder Russian cannon and carriage, a trophy of the Crimean War on display at Berwick’s ramparts.
Etal Castle reopens for the summer season tomorrow.