and then contracting engineer James Eads of St. Louis, Missouri to build the City-class ironclads. These excellent ships were built with twin engines and a central paddle wheel, all protected by an armored casemate. They had a shallow draft, allowing them to journey up smaller tributaries, and were very well suited for river operations. Eads also produced monitors for use on the rivers, the first two of which differed from the ocean-going monitors in that they contained a paddle wheel ( and ). The Union ironclads played an important role in the Mississippi and tributaries by providing tremendous fire upon Confederate forts, installations and vessels with relative impunity to enemy fire. They were not as heavily armored as the ocean-going monitors of the Union, but they were adequate for their intended use. More Western Flotilla Union ironclads were sunk by torpedoes (mines) than by enemy fire, and the most damaging fire for the Union ironclads was from shore installations, not Confederate vessels. Lissa: first fleet battle The first fleet battle, and the first ocean battle, involving ironclad warships was the Battle of Lissa in 1866. Waged between the Austrian and Italian navies, the battle pitted combined fleets of wooden frigates and corvettes and ironclad warships on both sides in the largest naval battle between the battles of Navarino and Tsushima. The Italian fleet consisted of 12 ironclads and a similar number of wooden warships, escorting transports which carried troops intending to land on the Adriatic island of Lissa. Among the Italian ironclads were seven broadside ironclad frigates, four smaller ironclads, and the newly built – a double-turreted ram. Opposing them, the Austrian navy had seven ironclad frigates. The Austrians believed their ships to have less effective guns than their enemy, so decided to engage the Italians at close range and ram them. The Austrian fleet formed into an arrowhead formation with the ironclads in the first line, charging at the Italian ironclad squadron. In the melée which followed both sides were frustrated by the lack of damage inflicted by guns, and by the difficulty of ramming—nonetheless, the effective ramming attack being made by the Austrian flagship against the Italian attracted great attention in following years. The superior Italian fleet lost its two ironclads, and , while the Austrian unarmored screw two-decker remarkably survived close actions with four Italian ironclads. The battle ensured the popularity of the ram as a weapon