In the era I study, most large-scale battles (and most single-ship actions, for that matter) were fought near land or at least landmarks. This is for the simple reason that before aerial reconnaissance and before radio enabled real-time communication from fast scouting ships, it was quite difficult to find another fleet at sea as ships were limited by their visible horizons and visual or audible signals (firing a gun, for example) to one another. Even 150 feet up a mast, a lookout has only about a 15-mile visible horizon, and though other ships' sails will poke above the horizon before their hulls do, that still limits range of scouting. So ships were more likely to find one another near common landfalls or at choke points in the ocean -- this is why the ports at Mahon and Gibraltar, for example, were useful to the British in the Napoleonic period.

The largest fleet battle fought out of sight of land during the Napoleonic period is the action commonly called "The Glorious First of June" in English, being fought on that date in 1794. This battle involved a British fleet attempting to take a French grain convoy, being protected by the French, and was fought about 400 miles west of Ushant in the open ocean. The British fleet defeated the French escorts, but the convoy escaped and carried its cargo to France.