What was the contributing factor to napoleons defeat at the battle of trafalgar?

Napoleon enlisted Spain’s help in forming a strong navy, but he was defeated anyway.

At the time of the Battle of Trafalgar, in 1805, France and Spain were operating in an alliance. Having Spain's navy helped strengthen France's chances at sea, but it was not enough. Napoleon was an artillery man, and the French navy never achieved the strength that Napoleon's Grand Armee achieved on land. The British navy was the strongest naval force on the seas. Plus, the British had Admiral Horatio Nelson in command. His surprising tactics in the Battle of Trafalgar yielded victory for the British Royal Navy against the combined fleets of France and Spain. Nelson himself received a wound in the battle that cost him his life, but the battle stands in history as his greatest victory.