Yes, that was one of three wars specifically engineered by Prussia to make Austria look bad.
The first one was against Denmark, and actually was the setup, where Prussia and Austria tried to force the political direction of the duchies of Schleswig and Holstein, by splitting them between the two.
3 Years later, Austria objected to holding the territories without approval from the German Diet, and that was all that Prussia needed as a pretext to wage war against Austria.
The third war was actually waged against France, started with the purpose of exploiting nationalist sentiment not only across northern German states, but also in southern and Catholic states. The latter weakened Austria's influence over a greater Germany.
To cap it all off, immediately after capturing Napoleon III, and laying siege to Paris during the fall and winter of 1870/1, Bismarck set up the coronation of Wilhelm I at the Palace of Versailles (how deliciously insulting that must have been to the French
Coronation of Emperor Wilhelm I at the Hall of Mirrors in Versailles 1871
Naturally, Austria was excluded from the German Empire, but Bismarck's idea was to keep Catholic control and non-German ethnicities outside of the new German state...
Or as we say in America, Bismarck was a real son of a [young female dog]
https://en.wikipedia.org/wiki/Otto_von_BismarckOtto von Bismarck in 1863
~ ~ ~
Well anyhow, I have to fold all of this into a global conflict. Prince Maximilian of Austria became Emperor of Mexico in 1864 until his execution in 1867, during which the Austro-Prussian war happened. This was directly tied to France's second Intervention in Mexico, where the Federal government of Benito Juarez went into hiding.
https://en.wikipedia.org/wiki/Maximilian_I_of_Mexico Emperor Maximilian I of Mexico, 1864
The American Civil War happened between 1861 to 1865, overlapping both the Maximilian Empire and the Maximilian Empire/French Intervention. In real history, Abraham Lincoln would basically have to ignore what was happening in Mexico. In alternate history, the risk of doing nothing would put the existence of the United States in extreme danger.
https://en.wikipedia.org/wiki/American_Civil_Warhttps://en.wikipedia.org/wiki/Abraham_LincolnUnited States President Abraham Lincoln 1863
Confederate States President Jefferson Davis 1865
The alternative history set up is to have Emperor Francis Joseph I of Austria give full support to young Prince Ferdinand Maximilian Joseph, as opposed to having the Austrian Emperor forcing Maximilan to sign a waiver where he renounced all nobility privileges in Austria before departing to Mexico (Nice big brother huh? I've known family members like that). Austria would have to be stronger, more organized, including Hungarian territories, and allied with France - the two latter of which are technically possible, because Austria-Hungary reorganized itself in 1867 and was stable enough until WW1.
https://en.wikipedia.org/wiki/Austria-HungaryEmperor Franz Joseph I of Austria 1865
Then I need the Confederate States to be in absolute desperate condition, but much stronger financially and technologically than they were. I need a Confederate stateman to be bold enough to suggest sacrificing unincorporated (non-states) American territory back to Mexico. Basically, cutting a deal with Maximilian where former Mexican territory is returned to Mexico in exchange for Austria and France joining the war against the United States.
The CSAA Alamo (aka the USAS Orca after the war) is a stratospheric capable (30 000 ft) craft, which could easily be developed as a hybrid aircraft designed to compete with designs from Solomon Andrew. The reason belong that Solomon Andrews was a northerner, and unlikely to cooperate with the Confederate States. So I need a genius counterpart tied with Austria's industrial and technical base - which if I understand was huge, actually. Someone in the US. Austria/Hungary or Germany would have to develop Duralumin alloys to build airship structures much earlier that in real history.
https://en.wikipedia.org/wiki/Solomon_Andrews_(inventor)
Solomon Andrews 1842
https://en.wikipedia.org/wiki/DuraluminMy Admiral Wilhelm character will (as a young captain) have to capture the CSSA Alamo in battle over the Desert of Sonora ("Franco American Aerial Battle")eventually turning it into the CSAS Orca.
Admiral Wilhelm at a dinner party in Austin, during his latter years c. 1899?

Naturally, I need to introduce lots and lots of adorable German/Austrian/Hungarian Luftschiffengel (Airship Angels) airship mechanics and engineers aboard the giant aircraft during the war

Again, the Luftschiffengel are
Engelfolk, a type of Elf-like 3rd Gender Catholic group from Southern Germany, Switzerland and Austria who are under religious persecution, and whose participation in the war is effectively part of their own diaspora (Englefolk Diaspora) caused by Bismarck's Protestant ideology in Germany.

Earliest known Daguerreotype of a Luftschiffengel c.1860
