What was the name of the battle fought against the French on 18th June 1815?

The battle fought against the French on 18th June 1815 is known as the Battle of Waterloo. This significant conflict marked the end of the Napoleonic Wars and the downfall of Napoleon Bonaparte, who faced a coalition of British and Prussian forces. The battle is particularly notable as it established a new political landscape in Europe, leading to a period of relative peace known as the Congress of Vienna.

In contrast, the other battles mentioned occurred in different contexts and periods. The Battle of Trafalgar, for instance, was a naval engagement fought in 1805 during the Napoleonic Wars, primarily between the British Royal Navy and the French-Spanish fleet. The Battle of Hastings took place in 1066 and was a pivotal event in the Norman Conquest of England. The Battle of Agincourt, fought in 1415, was a major English victory during the Hundred Years' War against France. Each of these battles is significant in its own right but does not pertain to the events of 1815, making the Battle of Waterloo the correct answer.