What would civil war era weapons to counter airborn pegasi look like? What kind of ammunition would they use and how would they be used to defend ironclads/wooden warships?

2029660
If I'm correct in guessing that by "Civil War", you mean "U.S. Civil War", I'd guess that they'd just use firearms.

Which type of firearm specifically, would depend on many factors, though.

2029660 Actually, the Civil War area did not have anything in the way of weaponry that would be effective against pegasi in flight. It was not until a couple decades later that the gatling gun was invented, and a bunch of them could make things more of a risk for pegasi in flight, but not too much, to be honest. The first weapons that could be considered even marginally effective against aerial attack did not appear until around WWI. That would be the first belt fed machine guns. Even then, it would take a sizable amount of them to pose a serious threat to a squadron of pegasi.

2029694 Actually Gatling guns were invented during the war and they were presented to the US army several times, they were just not accepted because the US army was a logistics nightmare at the time (it used over 30 different calibers) the Gatling gun would have just added another caliber of ammunition to that list.

2029713 My bad. Still, the gatlin gun, due to its fixed position nature, like that of a cannon, makes it impractical against aerial targets.

You could probably get some of them if you shot at them with cannons loaded with canister shot. I'm just now certain how you would get the gun to elevate that high, you would probably need a specially constructed, reinforced gun carriage.

The other issue comes in with ranging. It wasn't up until just before WWII that someone figured out how to figure out how far away an aircraft was so they could line up the AA guns properly. In WWI it was extremely difficult for ground guns to hit aircraft, their shots would fall short, or go long. Even into WWII it was calculated that over 90% of aircraft would make it through to the target, an idea summed up in the phrase "the bomber will always get through." It wasn't until after the war when effective anti air missile began to be employed that this became less true.

2029660
Graaaaaaaaaaaaaaaaape shoooooooooooooooot

I just remembered, the first anti aircraft guns were used by the Prussians during the 1871 Siege of Paris.

They were intended to shoot down the balloons the French were using to communicate with the outside world.
Here is an article that talks about it a little.

Worth noting that pegasi are very fast and agile; it doesn't seem like a stretch to say that Rainbow Dash could probably outpace any prop-driven plane, and definitely make turns faster and tighter than even a modern aircraft big enough to carry a pilot. Targeting pegasi in flight reliably would challenge Earth tech well past the end of WWII.

Of course, if these are normal Equestrians, their idea of aerial combat is probably to drop pies, trash and other harassing materials on their enemies, or else fly straight down to hoof-smacking range, and they wouldn't be expecting the noise, smoke or lethal force of Earthly weapons -- so it might be possible to drive them off with sheer surprise and a lucky shot or two, but that would be a very short-term defense. It would be much wiser for the humans to negotiate.

If we're assuming a worst-case scenario -- a large, organized force of lethally hostile pegasi with explosives or projectile weapons (possibly of magical nature), plus the training and mindset to make effective use of their assets in warfare, and a situation that's escalated past hope of peaceful parlay -- then without being at all facetious, I'd say the best bet for defense with 1860's equipment would be to find out if there are any griffins or spell-wielding unicorns around with a serious grudge against the pegasi.

Failing that, about the best they could do would be to fill the air in their immediate surroundings with enough lead to keep the pegasi at bay, and if you're talking about defending a ship on the water... I don't much fancy the odds there. Even if the pegasi don't have any sea pony allies, or just a Fluttershy with a few minutes to talk to nice Mr. Giant Octopus.

2029660

I would think they would use shrapnel weapons instead of bullets because the guns are inaccurate as it is.

2029967

We have only seen Earth ponies use pies as weapons, for one. Have you ever considered weaponized weather control?

2033324
Hadn't really thought of it in detail, no, but now that you bring it up, certainly rain, snow and wind would be among the non-lethal 'harassment' methods they might use in the 'normal Equestrians' situation. We've even seen Dash use a raincloud as a gesture of anger.

In the 'fully loaded battle pegasi' scenario... gotta say there's nothing but pure author fiat that could help an 1860's Earth force against an enemy able to bring in targeted tornadoes and lightning strikes -- especially if the pegasi know to aim for stores of gunpowder.

2029660 Airborne pegasi can't farm. That's their main weakness, in my opinion, and the only thing that would let humans defeat them.

I'd expect pegasi to exploit their advantage to their fullest extent, conducting deep raids with lightly-armed pegasi. As mentioned earlier, they could simply use the weather as a weapon if all else fails.

To counter them long-term I'd suppose something like a reverse Sherman's Savannah campaign - or more accurately, the Fabian defense against Hannibal: just destroy everything that isn't fortified strongly (e.g. on the level of the defenses at DC or Petersburg), retreating into strong points which pegasi have to spread themselves out for; low-level guerrilla campaigns to take out individual ponies. Of course, if you assume that pegasi eat grass to survive then you might as well surrender and get the whole thing over with quickly .

In the short-term, entrenchment is critical, because you need to force pegasi onto the ground where their advantages would be nullified and conventional weapons can be used. Fortified cannons angled to fire grapeshot and explosive shells in carefully-selected arcs would therefore be your best weapon. Valleys, urban, forest terrain in winter/storm/foggy/night conditions will be your best bet.

Ships are pointless in a pegasi vs. human battle except for monitors/ironclads in the shallowest of drafts or the most sheltered of waters (because of the weather). Might as well just beach them and use them as another fortified position.

First of all, let's say the pegasi are everyday equestrians. Hide in the Everfree forest, most ponies are scared of it, and then attack with grapeshot whenever need be. There you go. Now you know.