Let's talk about the big ones, the battleships, perhaps not seen since the Last Great War, perhaps yet to be built.
"With the cloud came a great thrumming sound, like many deep-voiced gongs being beaten rapidly in unison. The sound grew louder as the cloud began to fill the whole sky, casing a dark and ominous shadow over the Valley of the Morning. It was the allied air fleet of five nations.
Each ship was a thousand feet long. Each had a hull as strong as steel. Each bristled with artillery and great grenades which could be dropped upon their enemies. Each ship moved implacably through the sky, keeping pace with its mighty fellows.
Ships with Imperial crimson suns emblazoned on their white and gleaming hulls.
Ships with great black double-headed eagles glaring from the hulls of deepest scarlet, claws spread as if to strike.
Ships with massive three-color flags spread on backgrounds of blue.
Ships with cannon and bombs and crews, their booming engines like triumphant anticipatory laughter."
--Michael Moorcock, The Warlord of the Air
|Good times, bad times, you know I've had my share.|
There are blimps and balloons and sometimes those are enough, but when you want to move huge cargoes or large contingents of men or mount cannons, then you need a rigid airship, a dirigible. And it has to be filled with helium or a helium-like gas, because otherwise you are floating through the sky in a huge bomb: Oh The Humanity.
They can of course also be used for luxurious passage from one city to another for those that have the guilders and gold to spend that way. But imagine huge airships, bigger than the Hindenburg, and engineered far beyond that disaster-in-waiting. Rotors to compensate for the explosion of cannon; broadsides of guns and huge grenades to be dropped directly on opposing ships and forces. And such a quiet way to deliver great masses of troops.
Moorcock suggested the evolution of recoilless guns "that can stand in the air and shoot much longer and more accurately than cannon."
Imagine what even one of these Airships of the line could do, if it was suddenly, through powers scientific and arcane, thrust into a world that was not as advanced, or had simply never seen something like it. The men on a ship like that would have to decide what they wanted to do with all that firepower and speed. Decisions: yes...