How did Charles Darwin end up setting out on a voyage of discovery around the world aboard H.M.S. Beagle? Most descriptions of this turn of events start out with Capt. Robert FitzRoy seeking a naturalist to accompany him on the voyage in the early summer of 1831, but the story actually begins much earlier than this - to a time before Charles Darwin was even born. The emergence of Britain as the uncontested ruler of the seas after the Napoleonic Wars is where our story begins.
With this in mind, we turn back to the year 1805, four years before Charles Darwin was born. Ever since the French Revolution of 1789, the nations of Europe had been maneuvering to reestablish the balance of power throughout the continent. German and Austrian forces were invading France on and off since 1795 and Great Britain had maintained economic pressure on France by establishing a trade blockade. France made inroads into northern Italy and Egypt near the turn of the century, but their gains were soon lost.
This series of events lead us to October of 1805. The naval fleets of France and Spain tried to gain control of the English Channel in order to facilitate Napoleon's invasion of Britain. The British Navy responded to this threat by sending a fleet of warships under the command of Admiral Horatio Nelson to confront the French and Spanish fleets off the coast of Spain. On 20 October the French fleet tried to maneuver to the south, but Nelson caught them off Cape Trafalgar the next day. One of the largest battles in naval history ensued, with Admiral Nelson's fleet of 27 ships going against a fleet of 33 ships (18 French and 15 Spanish). In the end, the French and Spanish fleets were crushed. About 1,500 British seamen were killed or wounded, but not a single British warship was lost. The defeat at the Battle of Trafalgar ended Napoleon's plans to invade England, and the Napoleonic Wars came to a close ten years later at the Battle of Waterloo where the French Army was routed by Anglo-German forces. France surrendered soon after, and Napoleon was exiled to the island of St. Helena where he died in 1821.