The first detachment arrived in France June 10, 1918, but waiting for their equipment and preparing the trains meant that they did not leave for the front until Aug. 18. They served continuously from then until war's end on Nov. 11, 1918. They scored some notable successes, especially considering that "the great majority of shots were fired without adequate observation," and that they fired behind German lines at "unusually long ranges" and only "several hours after an Infantry attack" when reserves and ammunition cars were, it was expected, being rushed toward the front. Thus their fire was not continuous or random but measured and deliberate. Even so, they scored some notable hits including destroying a section of a moving supply train, ripping up an entire three-track line for a distance of some 100 yards, and scoring a direct hit on a German troop train with devastating results.
The American naval commander in European Waters, Vice Adm. William S. Sims, spoke highly of the naval railway guns, praising their "very excellent and valuable work, particularly in the recent pushes." Even so, the guns were already an anachronism. The increased use and effectiveness of aircraft, particularly bombers, with their greater flexibility and mobility, meant that the Naval Railway Battery would not be a mainstay in future wars. Nonetheless, its development and deployment highlights the U.S. Navy's ability to think innovatively and create and deploy new and effective programs quickly. That skill is transferable and is a hallmark of the U.S. Navy in the twentieth century.
As a final note, if you wish to see one of these Naval Railway Guns, there is one exhibited at Willard Park at the Washington Navy Yard. If you wish to learn more about these guns and the men who fired them, see a history of their service at "United States Naval Railway Batteries in France."