Iron and coke and chromium steel.
Most of the discussion of Civil War gunboats and ships takes naval artillery for granted and leaves artillery almost completely out of the analysis, emphasizing armoring of the ships. From personal experience you want be on the side of the battle with biggest most accurate guns. These take time to produce and require a sophisticated and robust industry to produce them. The Confederate boats and batteries had to make do with 12- and 24-pounder artillery and some 32-pounders, most of which (1200) were captured at Gosport early in the war. The Union was in the process of replacing its 32-pound naval guns when the war began. It had lots of them to spare for the gunboats. When the war started the Union had been manufacturing larger replacement guns for years, beginning in the mid 1850s, and had a significant capacity for manufacturing more of them (Alger Foundry, West Point Foundry, Seyfert & McManus, Fort Pitt Foundry). Union gunboats, for example mounted two to four 8-inch guns (62 pounders), two to six 32-pounders, and two to six 42-pounders. By 1863 and the Vicksburg campaign Union gunboats like the USS Carondelet would carry three 9-inch guns, four 8-inch guns, a 50-pound rifle, 32-pounders and 42-pounders. By 1864, two 100-pound rifles were added. Even in the case of the British built Confederate raiders, the Union had a fire power advantage. In the famed sea battle between the USS Kearsarge and CSS Alabama, the Kearsarge mounted two 11-inch Dahlgren pivot guns firing 140-pound shot compared to the Alabama's single 100-pounder and single 68-pounder. In other words, the Union's artillery manufacturing capability meant the Confederates were completely outgunned on the Mississippi and at sea.
The irony of this military advantage was that slavery helped build it. An analysis of the West Point Foundry's production for civilian buyers shows that much of it was destined for the South, including the first locomotive entirely produced in the United States, Best Friend of Charleston. Prior to the outbreak of Civil War hostilities, the West Point Foundry had produced the huge Dahlgren guns mounted on the USS Monitor.
"I saw it standing forlorn and lost, in disrepair, high on its rock overlooking our beloved Hudson and I nearly wept at the sight."-- Helen Hayes, 1971
For those [Irish immigrants] who gained employment at the West Point Foundry in Cold Spring, a chapel was established to serve them and their families. Foundry owner Gouverneur Kemble donated land and funds for what would be the first Catholic church north of Manhattan.
