Share This Article

Intelligent Whale, the war’s most advanced submarine, has been sitting quietly for years in a New Jersey museum. Many thought it was a postwar machine. It’s time to rewrite American naval history.

It’s easy to get swept into the dustbin of history. Documents get lost, memories fade and details get confused. With luck, perseverance, and skill, however, what was once lost can be rediscovered. Or in the case of Intelligent Whale, a submarine that has been hiding in plain sight for years at the National Guard Militia Museum of New Jersey in Sea Girt, what was misunderstood can get its full due.  

It’s a stunning discovery. For many years, most assumed that the submarine was a postwar invention, built in 1866. That date was based on papers that showed the U.S. government purchased it from one Oliver Halsted in that year. But New Jersey court records and National Archives documents prove that the vessel had hit the water in 1864 and is the only surviving Union submarine from the war. Many current Navy officers and Civil War scholars had wished for a surviving Federal counterpart to the Confederate submersible CSS H.L. Hunley. Now they have one.

Those documents establish August 4, 1864, as the date three Federal naval officers walked down a long dock at Port Morris, Long Island Sound, N.Y., toward a mysterious, partially submerged iron vessel. With orders to evaluate and report on Intelligent Whale’s worth as an engine of war, the officers shook hands with a Massachusetts inventor, Scovel Merriam, and his colleague Woodruff Barnes, two founding members of the recently established American Submarine Company. For nearly a year Merriam and his partners had been petitioning the secretary of the Navy and various high-ranking naval officers to use their new submarine for a specific and increasingly critical purpose: to clear Charleston Harbor by removing underwater obstructions, blowing up gunboats, and cutting Rebel telegraph lines. Merriam and Barnes were about to get the chance to prove the military worth of their invention.

By that summer of 1864, both North and South had constructed several underwater vessels with mixed results. In the fall of 1861 the Federal navy built USS Alligator, a 50-foot submarine originally designed to sink the Confederate ironclad CSS Virginia. It was completed too late to make that attempt, however, so the Navy towed Alligator down the Atlantic Coast instead. In 1863, it was dedicated to clearing Charleston Harbor of mines and other lethal obstructions, but before it could get to Charleston, Alligator was lost in a gale off Cape Hatteras.

On February 17, 1864, Hunley attacked and sank USS Housatonic, a sloop-of-war that had been on blockade duty off Charleston. Within days after that successful attack, the following lines appeared in an editorial in the Army and Navy Journal: “The destruction of the sloop-of-war Housatonic, off Charleston Harbor, demonstrates very conclusively that the Rebels have anticipated us in the practical application of engines of submarine warfare. The fact is a mortifying one, but it should invite our inventors to perfect more speedily the appliances…. Our inventive reputation is at stake in this matter, and it will never do to let the Rebels get the start of us in perfecting and utilizing these submarine engines.”

Scovel Merriam, a 41-year-old discharged engineer who had served a year with the South Atlantic Blockading Squadron, was ready for that challenge. In the summer of 1863, he had approached Rear Admiral John Dahlgren with an innovative idea for removing underwater obstructions in Charleston Harbor. Merriam proposed to the admiral that he and a small crew in a submarine of his own design would enter the harbor and “remove the obstructions in the ship channel…such as piles driven, hulks sunken, chains, netting etc.” and cut “anchorage and exploding wires of torpedoes therein and destroy or make use of [Rebel] telegraph wires crossing said channel.”

In addition, Merriam offered to create “a channel two hundred feet wide and exactly buoyed out so as to direct any vessel safely through,” and throughout the undersea operation to “be in direct communication with the commander of the fleet outside of the harbor by laying as we proceed to the obstructions a telegraphic wire.” For this service Merriam and his partner, William Kasson, requested of the admiral that $250,000 be paid to them upon completion of their mission.

Soon after receiving the offer, Admiral Dahlgen passed it on to Secretary of the Navy Gideon Welles, and informed him, “I am willing to recommend such an agreement.” In response to Dahlgren’s endorsement of the plan, Welles responded: “You are fully authorized to take all measures to effect the great object entrusted to you…. You are better informed than the Department, and consequently can better judge and decide in regard to the proposition of Messrs. Merriam and Kasson…” On September 12, just days after receiving a copy of the offer and Dahlgren’s endorsement of the daring plan, Secretary Welles informed partners Merriam and Kasson that “Admiral Dahlgren is fully authorized to take all necessary measures to effect the removal of obstructions in the harbor of Charleston, and the Department would respectfully refer you to him.”

With consent from Secretary Welles, Admiral Dahlgren encouraged Merriam to proceed with his plans, and by early November 1863, Merriam had entered into a contract with Northern industrialists Cornelius Bushnell and Augustus Rice to “construct, finish and complete a submarine apparatus” (it is unclear what became of Merriam’s original partner William Kasson). With $15,000 delegated for the construction of the vessel, Merriam and his partners threw themselves into the project and were soon overseeing the fabrication of the submarine’s various components.

For the next four months artisans in Newark worked through the New Jersey winter casting various components while workers riveted large, half-inch thick steel hull plates to internal iron ribs. Some laborers installed high-pressure valves and air pumps, while others filed down external rivet heads to provide as smooth a hull surface as possible. Thick glass viewports were riveted into place.

Just three months or so after Secretary Welles and Admiral Dahlgren gave Merriam the go-ahead, newspapers in both the North and the South reported H.L. Hunley’s sinking of USS Housatonic off Charleston. As word of this dramatic event circulated throughout the nation, Merriam and his partners decided the time was right to reestablish contact with the Navy Department. On February 29, 1864, Woodruff Barnes— on behalf of Merriam and his partners—sent letters to both Secretary Welles and Assistant Secretary Gustavus Fox. In his letter to Fox, Barnes wrote, “I addressed the Secretary of the Navy recently and again today in regard to proposed operations in Charleston Harbor in removing obstructions and blowing up gun boats, torpedoes etc. Our vessel is nearly completed, the plan of it you have seen…. Our vessel has been quality built and the public knows nothing of it. We can be ready in about two or perhaps three weeks.” On March 2 Secretary Welles telegraphed Barnes, “When your submarine boat is completed the Department will order its examination at your request.”

By mid-April partners Merriam, Bushnell and Rice— with Barnes acting as secretary and treasurer—formed the American Submarine Company. Although completion of their submarine took a bit longer than the “two or perhaps three weeks” mentioned in Barnes’ letter, by late July 1864 the vessel had been transported to New York and was undergoing trials in Long Island Sound. After receiving that news, Secretary Welles ordered an examination of the Intelligent Whale, setting stage for August 4.

The report filed by the inspectors after that trial indicates that Merriam and his partners had not been prepared for a comprehensive evaluation of their submarine. The naval inspectors stated that “No attempt was made to navigate the vessel when submerged, but upon the surface the vessel barely moved through the water…no compressed air was furnished for experiment…The vessel was submerged in 15 feet of water…Six men were in the boat during this trial, and experienced no inconvenience. The equilibrium of the vessel was perfectly maintained…No provisions were made for submarine operations in armor (in modern terms this means that no diver was used to demonstrate how a person could exit the submarine and work outside)…In conclusion we would state that the vessel was offered for inspection before the designers were prepared to illustrate the several objects for which she was built. In our opinion the vessel can only be used as a self propelling diving bell, to make submarine explorations and preparations for removing obstructions in comparatively smooth and peaceful waters.”

Although representatives of the American Submarine Company petitioned Secretary Welles for a copy of the unflattering report, the secretary refused and subsequently turned down the group’s offer to operate the vessel in Charleston Harbor. Their original plan in tatters, the investors quickly decided to bring their secret weapon out of the shadows. Within weeks they arranged for more comprehensive demonstrations for the Northern press. The following article regarding one such demonstration appeared in the October 1864 edition of Scientific American.

“A Submarine Vessel: Entering the singular vessel from the top, the door was closed, and the order, ‘Men to your places,’ given to the little crew, who promptly obeyed. When everything was ready, Mr. Merriam turned some valves and the compressed air came hissing in, producing an unpleasant sensation upon the drum of the ear, of which one was at once relieved by inspiring and swallowing. The vessel seemed perfectly under control, for we stopped when half down to the bottom, and raised the door on the bottom of the boat…we were on the bed of the river, 20 odd feet underwater, this distance requiring an additional pressure to resist the water with the door open. We could stand on the bottom of the river and not wet our feet, and at that distance underwater could easily see to read by the light that came in at the glass windows…. To return to the rest of the world only a few strokes of the pumps were necessary; the air rushed out of the bottom and the boat was quickly on the surface of the water. We moved with a propeller easily under as well as upon the water, and in all respects the vessel worked so completely that its success is undoubted.”

The good notices in such a widely read and respected publication brought the sub to the attention of Oliver Halsted, an influential Washington lobbyist and trusted confidant of President Abraham Lincoln. Within months Halsted became the majority stockholder in the American Submarine Company and, by early March 1865, the submarine’s owner. Enjoying easy access to President Lincoln, Halsted presented a plan to the commander in chief to use the submarine to remove Confederate obstructions in the James River near Richmond. Lincoln dispatched Halsted southward to meet with Lt. Gen. Ulysses S. Grant, who endorsed Halsted’s plan.

In early April, however, the Confederate government abandoned Richmond, and Halsted sold Intelligent Whale to the U.S. government in 1866. Various naval engineers experimented with the vessel, and numerous articles regarding its underwater trials appeared in the press during the last decades of the 19th century. For many years the submarine was on display as a curiosity at the Brooklyn Navy Yard where—according to an 1897 article in The New York Times—it waited to be sold as scrap to the highest bidder. Spared that ignominious fate, Intelligent Whale, originally designed in 1863 to enter Charleston Harbor, is now poised to receive the attention it deserves for its technological advances and for its significance as the Union’s only surviving submarine.


Mark K. Ragan served as the historian for the project that raised CSS H.L.Hunley. He is also the author of Union and Confederate Submarine Warfare in the Civil War (Da Capo Press), and other books about the war on the high seas. A diver, Ragan has participated in numerous underwater explorations.

Originally published in the May 2008 issue of America’s Civil War. To subscribe, click here