With the sun setting over this faded port city, Queen Elizabeth II lit a beacon Friday to commemorate the 200th anniversary of the Battle of Trafalgar, in which Britain's Royal Navy defeated the French and Spanish fleets and cemented its naval supremacy for the next century. Bells tolled aboard British vessels around the world and wreaths were laid at the site of the decisive battle just off Cape Trafalgar in southwestern Spain. In the nearby port of Cadiz, descendants of sailors who fought in the battle joined military leaders to pay homage to the 7,000 who died in the fighting....