First off the gattling gun did not play a major role in any war. They were excessivly expensive, had accuracy that made them useless at more than 50 yards, they constantly jammed, and the shots were low velocity shots and usually didn't kill a person even if shot (durring an era when a musket shot to the leg usually meant death.). 2nd, they never saw action even in the civil war, the war they were made for. Wait for WW1 to use a machine gun.
2nd, zepplans never saw warfare outside of europe
and 3rd the ironclad was invented by the french in 1855, then the british built 2 in 1856. Both had to be towed into location.
The first self propelled ones were again by the french, followed by the british in 1859. The Americans paid french designers to work on their ironclads even. and the battle between american ironclads was unimportant. Not until 1864 could you say Ironclads made a difference (spain vs. austria/hungry). So for them, no, not in this game. However maybe in an X-pack