The Royal Maritime Museum at Greenwich is showing Broadsides: Caricature & the Navy throughout January.
The show covers the history of the Napoleonic wars against France when the country was preoccupied in a “battle to control the dunghill”.
By 1815 Britannia actually ruled the waves as the cheerful image above indicates. You can see “Boney’s Invincible Armada” and gather more information about the show at the ship-shape site right here.