What is commemorated in Great Britain by Trafalgar Day every 21 October, and by the name of Trafalgar Square in London?

Question

In the first half of the 18th century in Great Britain, what drug became so popular, particularly in London, that several laws were passed trying to restrict its use?

Answer 1

A 19th century sea battle
The Battle of Trafalgar was a sea battle fought on 21 October 1805 between the British Royal Navy and the combined fleets of the French Navy and Spanish Navy, during the War of the Third Coalition (August–December 1805) of the Napoleonic Wars (1803–1815).