This is "An Allegory" painted in the French style during the 19th century. At first glance, it appears to be a dramatic scene with Attila driving Beauty, Art and Pleasure before him. If you look closely, you'll notice that much of the painting has been preserved with paper, a result of damage sustained in a flood back in 1928.
This painting was once attributed to Eugène Delacroix due to some similarities with his own work, particularly a mural he painted at the Palais Bourbon in Paris. However, it now seems unlikely to be one of his pieces, mainly because of the fake signature.
Despite its uncertain origins, "An Allegory" remains a thought-provoking image, evoking questions about the relationship between civilisation and barbarism.
An Allegory hangs in The National Gallery on Trafalgar Square, London — free to enter. Point your phone at any artwork there and audioguide.london plays a free audio guide in six languages — no app download needed.