Maillé-Brézé is a French T 47-class destroyer, launched in 1953 in Lorient and named after admiral Jean Armand de Maillé-Brézé (1619–1646).
She was decommissioned in 1988 and became a museum ship in Nantes.
However, at the beginning of this month (May 2016), she slipped her moorings in Nantes to be towed up the coast (3½ days at 6 knots) to Dunkirk, where right now, she is being filmed in the role of several ships featured in a WW2 movie, Dunkirk.
The historical drama is written, directed and co-produced by Christopher Nolan, and stars Tom Hardy, Mark Rylance and Kenneth Branagh. It is due to be released July 2017.
Like all movie stars, Maillé-Brézé has spent a little time in make-up, having a paint job and having some of her more modern gear – missiles, radar, etc – removed or covered up. She will return to Nantes in July after filming.
UPDATE: It turns out she played the role of two British destroyers HMS Vivacious and HMS Vanquisher with their different pennant numbers painted on her port & starboard sides.