Was the "Bruce-Partington Operation" the first submarine?

Not by twenty thousand leagues.
Believe it or not, back in 1620 – the year the Pilgrims landed at Plymouth Rock -- Cornelius Van Drebbel, a Dutch doctor living in England, built and operated a small submersible boat. It was powered by oarsmen, the oars protruding through flexible leather seals. Snorkel air tubes were held above the surface by floats, thus permitting a submergence time of several hours. Van Drebbel successfully maneuvered at depths of 12 to 15 feet below the surface of the Thames River.
Van Drebbel followed his first boat with two others. The later models were larger but they relied upon the same principles. It is reported that after repeated tests, King James I of England rode in one of his later models to demonstrate its safety. But even royal favor failed to arouse the interest of the British Navy.
And in 1747 an unidentified inventor introduced a most unusual device for submerging and surfacing. As reported in a British periodical in 1747, his craft was to have had a number of goatskins built into the hull. Each was to be connected to an aperture at the bottom. He planned to submerge his vessel by filling the skins with water, and to surface it by forcing the water out with a twisting rod. Thus, we have what was probably the first approach to the modern ballast tank (the basic engineering problem which the Bruce-Partington plans apparently addressed).

But it's us folks down here in the American South who can lay claim to the first successful submarine attack. A steam boiler was converted into a submarine for the Confederate States of America by H. L. Hunley. The David propelled at four knots an hour by a hand-driven screw, but sank repeatedly in trials at New Orleans, Mobile, and Charleston. Hunley himself was drowned with eight other crewmembers in Charleston Harbor. But this submarine was raised and renamed Hunley.

The concussion wave swamped Hunley and it sank with Housatonic, but it had proven that the submarine could be a valuable weapon in time of war ... decades before the loss of the Bruce-Partington plans.