Work on the submarine began in early 1864. On June 14, Kroehl wrote to the Navy’s Chief of the Bureau of Yards and Docks to press his case: “I sent you last week a pamphlet issued by the Pacific Pearl Company, for whom I am now building a submarine boat… In the operations against some of the rebel forts and harbors I have no doubt the Navy Department will require submarine boats, and I think it would be advisable to bring this to the attention of the Honorable Gideon Wells, and have the plans examined by a proper board.” The following day, he received a reply. The plans were interesting, and he should send them to the Secretary of the Navy. Kroehl did so, and on June 18, just four days later, was told by Secretary Welles to present his plans to W.W. Wood, the Chief Engineer of the United States Navy.
Sitting in a folder in the National Archives is Wood’s meticulous eighteen-page report on Kroehl’s submarine, written after he toured the vessel as it was being built in New York. Wood also drew up a large plan of the submarine — a sheet of paper that rolls out 3 feet — fully one-twelfth of the length of the actual craft. Reading the report and perusing the plan, it is obvious that the submarine on the beach at Isla San Telmo is the same vessel. The chamber on the top, according to Wood, was the “compressed air chamber… it has a semi-elliptic form and is built of two shells of best boiler iron % inch thick, the different pieces lapping 4 inches are double riveted with % inch countersink rivets, and braced with ribs of 3½” × 3” × ½” angle iron and 1 inch braces.” That kind of intricate detail is invaluable to an archeologist.
Wood’s report goes on to explain how a compressor inside the submarine was used to build up sufficient pressure to not only clear the upper ballast chamber to enable the submarine to rise but also to pressurize the hull to allow the unbolting of bottom plates so that the crew could reach into the water and harvest pearls — or to serve the purposes of war. This self-propelled “lock out” dive chamber — which many historians think is an innovation of the twentieth century — was designed and built in 1865. Wood’s report concluded by enthusing that “the uses to which a boat… in Naval Warfare, would be the removal of submerged obstructions in the channels of rivers and harbors. Approaching hostile fleets at anchor and destroying them by attaching torpedoes to their bottoms and exploding such localities as are commanded and covered by the guns of an enemy. The importance of a successful application of the principles involved in such a vessel for such purposes are of much importance and can not be too highly estimated.” Julius Kroehl couldn’t have said it better himself. It is a glowing endorsement, and I wonder what happened. Why didn’t the Navy buy the sub?
Part of the answer is that the submarine was not yet finished. Another is that the war was winding down. Most of the major ports of the South had fallen, the Mississippi was secured and the collapse of the Confederacy was just a few months away. With the end of the war imminent, the Navy Department probably viewed Kroehl’s submarine, brilliant though it was, as coming a bit too late. A genius, yes, an engineering breakthrough, yes. But the time for such an invention to help “win the war” had passed.
And so the Union Navy, which had already invested much in the unfortunate sub Alligator, declined Kroehl’s offer. But there were still pearls to harvest in Panama, and the Pacific Pearl Company used Wood’s letter as an endorsement, publishing it in a promotional pamphlet to sell stocks in 1865. They mentioned it again in an article in the May 31, 1866, edition of the New York Times:
Yesterday afternoon there was a private trial of the Pacific Pearl Company’s Sub Marine Explorer, in the dock foot of North third-street, Eastern District… Julius H. Kroehl, engineer, with Frederick Michaels, August Getz and John Tanner, entered the explorer through her man-hole, which being finally dosed and the signal given the boat was submerged, and for an hour and a half she traversed the bed of the dock. During the submersion the friends of those onboard the boat exhibited considerable anxiety for their safety, but then at last when she rose to the surface… they gave vent to their feelings in repeated cheers. These were again and again repeated, when the engineer held up a pail of mud which he had gathered at the bottom of the dock, showing conclusively the success of the experiment.
But even if the end of the war had not ended the Navy’s interest in submarines, then the failure of its own great wartime experiment, the submarine Intelligent Whale, decisively closed the door. After three years of work, the shipyard finally launched Intelligent Whale just a month before Kroehl’s highly publicized demonstration of Sub Marine Explorer. Unlike Kroehl’s boat, Intelligent Whale was not a success, reportedly killing dozens of crewmen in various trials and tests. Renamed “Disastrous Jonah” by wags, Intelligent Whale ended her days laid up, unused. Thirty-one years would pass before the U.S. Navy acquired another submarine, in 1897. Another seventeen years would pass until a submarine again sank an enemy vessel in wartime, when the German U-21 sent HMS Kent to the bottom of the North Sea, an act that heralded the opening of a new and far deadlier campaign of submarine warfare and that changed the way war was fought at sea.
After the demonstrations of Kroehl’s submarine, both he and his invention left New York. Sometime that fall, or early the following year, the Pacific Pearl Company shipped Sub Marine Explorer to the Pacific coast of Panama. There, it worked for a while, according to a report published in a company prospectus published in or around 1867, and a 1902 article reported that at Panama, Sub Marine Explorer “was successfully used, and Mr. Kroehl said, the divers employed in the boat enjoyed better health than the other divers… The bottom of the boat could be opened or closed as desired. When exploring in considerable depths the bottom was closed, to save the crew from the heavy pressures.” But at some stage the submarine was abandoned, perhaps as early as the fall of 1869. Kroehl was not around then. He had died of the “fever” in Panama two years earlier.
Why there and when? Just off the beach where Explorer now rests is a large pearl bed in about 100 feet of water, and it was there that the submarine was working in 1869 in the last known contemporary mention in print. Perhaps Explorer was left on the beach after something broke, or perhaps the pearl bed was fished out. Perhaps, without Julius Kroehl around to care for his invention, no one else could. We may never know. Someone did try to salvage the wreck at some distant time, because the conning tower is wrapped with wire cable, and the tower and the hull around it are slightly deformed from torquing from an offshore direction, as if someone had tried to pull it off the beach and failed. And some features are missing from the submarine — the propeller and the conning tower hatch are gone, stripped for salvage.
Julius Kroehl’s Sub Marine Explorer, now abandoned on a little-known island off Panama, was the only successful “Union” Civil War submarine, the brainchild of an undersea pioneer whose service in the war was relegated, along with his magnificent invention, to the backwaters of history. History is often dominated by “what if?” What if Kroehl had invented his submarine earlier and sent it into combat against the Confederacy? What if, on one of those missions, Sub Marine Explorer had sunk, carrying vessel and crew into the honored halls of wartime sacrifice like H.I. Hunley? There would have been two Civil War submarines, forever linked in history. But events didn’t work that way, and Sub Marine Explorer had a more peaceful career, far from home, where the memory of her location and identity faded with time, to be resurrected only by chance by a vacationing archeologist.