The brass plaque was taken from the fence which surrounds a memorial oak sapling on the battlefield site at Branxton.
The sapling was planted on November 17 last year, by Dr Chris Burgess, president of the Till Valley Archaeological Society (TillVAS). It was the first of many acts planned to mark the 500th anniversary of the battle, which wasthe largest in terms of troop numbers between England and Scotland.
James Bell, chair of Coldstream’s 1513 club, described reaction to the vandalism.
“This is a very sad reflection on our society, that someone could stoop so low,” he said.
“I am absolutely shocked by this desecration. We on the Scots side view this site at Branxton as a war grave.
“The scrap value of the plaque would be just a few pounds but the emotional value is immense.”
TillVAS secretary Maureen Charlton added: “This is a desecration of a memorial to the dead of both nations.
“It is awful to think that something like this could happen in this peaceful, friendly area.”