Which country was Britain up against in the Battle of Waterloo?

The Battle of Waterloo, a pivotal moment in European history, took place in 1815. It marked the final defeat of Napoleon Bonaparte, the French Emperor who had dominated much of the continent for nearly two decades. Napoleon's ambition to conquer Europe had led to a series of wars, and Britain had consistently opposed him, often through alliances and naval power. The battle itself was fought near Waterloo, which is now in Belgium, but at the time was part of the United Kingdom of the Netherlands. The Duke of Wellington led the British and allied forces against Napoleon's French army. While other European powers like Prussia also played a crucial role in the victory, the main adversary Britain faced at Waterloo was undoubtedly France. Germany, Italy, and Spain were not the primary opponents in this specific battle, although they were involved in other conflicts during the Napoleonic era. So, the correct answer is France because Waterloo was the decisive battle that ended Napoleon's reign and his French Empire's dominance.