On October 21, 1805 – 209 years ago to this day – Admiral Nelson of the British Royal Navy fought with the combined forces of the French and Spanish Navies off the southern coast of Spain in the Battle of Trafalgar. Although the British were outnumbered and outgunned, Nelson annihilated the Franco-Spanish navies in less than three hours. The victory insured the supremacy of the British Empire and signaled the decline of the Spanish Empire.
Admiral Nelson had been playing a game of cat and mouse throughout the Atlantic with Admiral Villenueve of the French and Spanish fleets, and Nelson had grown impatient. Villenueve had led Nelson to the Canary Islands in the hopes of forcing Nelson to leave Great Britain undefended so Napoleon could Great Britain without having to confront the Royal Navy. Consequently, when Nelson received news that Villenueve and his fleet were stationed at Cadiz, Nelson moved to attack. At Cadiz, the French and Spanish forces could easily capture British trading ships as they exited the Mediterranean Sea.
In late September, Nelson stationed his naval fleet off the coast of Cadiz and prepared a visionary battle plan. The prevailing opinion in naval warfare at the time was to approach the enemy in “one line of battle and then engage broadside in parallel lines.” This tactic allowed the naval commander to signal to their ships easily, and it was simple for a ship to disengage if under heavy fire, therefore minimizing casualties. This strategy often led to inconclusive battles.
Nelson wanted to force a confrontation, so he developed a radically different tactic. He divided his forces into two columns, which sailed perpendicular to the enemy’s line of fire and therefore cut the enemy’s line into three different sections. His strategy was to take out the flagship first, from which Villenueve would command his fleet. This tactic would incite chaos in the enemy fleet. Because it depended on speed, Nelson ordered all of the ships’ sails to be opened in order to engage the enemy as quickly as possible. Once the British ships met the enemy line of fire, they would fire onto the unarmed parts of the ships.
On October 19th, Villenueve sailed out of the port of Cadiz to confront Nelson. The French and Spanish navies boasted a 30,000-man fleet of 22 vessels, while the British had only 12 ships consisting of 17,000 men. Villenueve drew Nelson into Cape Trafalgar, and the British opened fire at 12:25 PM on October 21st. 
Despite being outnumbered, the British had superior firepower. For every cannon that the French and Spanish fleets could fire, the British could shoot 2-3 more. The British targeted the Bucentaure first, Villenueve’s ship, and within ten minutes they had killed 200 men. The first ship surrendered 45 minutes later, and by 3:30PM the British victory was clear. The British had captured 22 enemy ships and not a single British ship had surrendered.
The battle was the most decisive naval victory of the Napoleonic Wars. The French fleet never again seriously challenged the British Royal Navy. Nelson’s victory affirmed the supremacy of the Royal Navy over the world’s oceans. The British had also decimated a large portion of the Spanish navy’s ships. Without a large fleet, Spain could not maintain control over its overseas colonies. The three hour-long Battle of Trafalgar drastically undermined the ability of the Spanish navy to defend itself. The later invasion of Napoleonic forces into Spain in 1808 further isolated the Spanish Empire.