The Battle of Trafalgar was a sea battle fought on 21 October 1805 between the navies of France and Spain on one side, and Great Britain on the other. The battle took place near Cape Trafalgar, which is in southwest Spain. The battle ended with a clear victory for the British forces. This allowed Britain to become the world's largest sea power for 100 years. The Battle of Trafalgar was the most important sea battle of the 19th century.