English artillery buckle

typical plaque for a bandolier, as already in use at the end of the 18th century and during Napoleon's Campaigns against France: in brass, with two brackets on the reverse, engraved on the recto with royal crown and initials "3AT" (3rd Artillery Train) ; in good condition with the right patina of time never "revealed" by cleaning; very rare By family tradition found years ago in Portugal Measures 11.5 x 8.5 cm