Alpha Shade

Alpha Shade is a webcomic by Joseph and Christopher Brudlos. Set both on Earth and the titular parallel world, it begins in the middle of a land-grab war waged using roughly WW 1-level technology, but with added Intellectual Animals and flying battleships, between two Empires (the Great Northern Empire and the Great Southern Empire), then jumps back in time to the build-up to the war.

The main character, Laura Stone, appears to be a normal college student on Earth, but by the period covered by the first chapter has become the leader of a small country in the Alpha Shade world and a respected military leader. How she made this transition is yet to be revealed. 'Main character' is a slight misnomer here, as the authors by their own admission write every character as if they consider themselves a protagonist, and spend a great deal of time fleshing out (and occasionally killing) other characters. These include:

Nicole, Laura's adoptive sister on Earth, Nick and Justin, their best friends, Molly, their roommate, and Todd, Nicole's boyfriend.
Several groups of soldiers in Laura's army in Chapter 1.
Lord Hechinger, a noble of the Great Northern Empire leading an expedition to Earth to recover something called the Thrall Stone, and his subordinates.
Lord Rastislav, Hechinger's opposite number from the Great Southern Empire, and his subordinates.
The three daughters of House Shapira of the Great Northern Empire, all of whom are riders of the giant war-birds known as Flyers.
The sentient, psychic cats and panthers that manipulate the Alpha Shade world's politics.

Alpha Shade has been noted for its stunning computer-drawn art, intriguing multi-threaded story and interesting characters, and is well worth a look. The first two chapters have been released in print and are available from the website's store.

Tropes used in Alpha Shade include:

Action Girl: Kayla, the Shapira sisters, Laura.
Airborne Aircraft Carrier
All There in the Manual: The print books, the guide sections on the website and comments by the creators give a lot of background information and detail on the setting and some of the characters.
Anyone Can Die: On several occasions, some details of a new character's background and personality will be revealed, suggesting they are going to be around for a while. Then they die.
Applied Phlebotinum: This is what keeps the flying battleships up.
Aristocrats Are Evil: Mostly played straight - all the Alpha Shade aristocratic characters except the Shapira sisters (and possibly Laura, depending on the nature of her leadership role) seem to be pretty unsympathetic.
During the War: Chapter 1.
The Empire: Two of 'em.
Intellectual Animal: Flyers, Panthers and Imperial Cats.
MacGuffin: The Thrall Stone, possibly; either that or an Artifact of Doom.
Masquerade: Possibly multiple levels. Our world doesn't seem to know about theirs. There is concern when a Flyer makes a brief appearance over an Earth city. On the other hand, they're using technology that's ~70 years behind Earth. Given the nature of war (from what we've seen, a single squadron of modern fighter jets could probably win for either side single handedly) is there something stopping them from knowing too much about us?
Mauve Shirt: as was said before, the authors are very good at giving distinct' likeable personalities to even minor characters. As in "bite your fingernails and curse at the screen while watching them die" good.
Ordinary High School Student: Ordinary College Students, in this case.
Portal Network: The Gatestones used to travel between Earth and Alpha Shade seem to fulfil this role, but are more portable than usual.
Redshirt Army: Partially subverted by Laura's army; at least some of them seem to be competent, and several are individually characterized. The elite Flyer Riders tend to mow them down like flies at times, though.
Talking Animal: The telepathic Panthers and Imperial Cats. Flyers seem to be able to communicate with their riders, but haven't been shown with actual dialogue.
Trapped in Another World: Subversion: it seems to be possible to travel between Earth and the Alpha Shade world at will as long as you have a Gatestone. Whether it's in a different universe from our Earth, or somewhere else in our universe, isn't yet clear.