The original game in the series was published by Yaquinto in 1979. Yaquinto published an expansion the following year, which covers scenarios beyond the American Civil War. Evidently the rules were revised in 1980 also.
In 1987, another publisher (3W) released Shot & Shell--a self-contained game which was clearly designed to be fully compatible with Ironclads and its expansion (it even includes a conversion chart for The Ironclads). Shot & Shell adds new maps, new ships, new scenarios--and expanded rules which enhance the original game in many ways. A major addition in Shot & Shell is a fairly detailed land-warfare system, which enables players to re-create amphibious actions or cooperative land-water engagements.
All three above games have long been out of print, but the first two (The Ironclads and the Ironclads Expansion) were reprinted by Excalibre and are currently available from Decision Games. The reprints are reputed to be virtually identical to the original games, with the notable exception of the components. The main difference there is that the ship counters were printed as side-view images, whereas the originals were top-view images.