Non-Star Trek space opera and military scifi books you enjoy

I was recently telling someone about the two volume Steampunk Soldiers series from Osprey. It's set around the turn of the 20th century on a world where a new element (hephestium) fell on Earth in 1862 from a meteor shower, causing an industrial revolution earlier than our timeline. By the early 1900s, things like aircraft, submarines, combat walkers, and automatic weapons (among others) are already common in most nations.

Because the bulk of the deposits landed in parts of North America, it dramatically changed the evolution of history. The American Civil War lasted twice as long and the Confederacy won, due in part to using different tactics as well as gaining better economy with the hephestium they acquired. They also blocked the Union attempts to gain control of the Mississippi River. It's hinted that the two halves might reconcile their differences and perhaps even reunite at some point.

British Canada became the jewel in the imperial crown, rather than India (which is part of the Empire but suffering stronger revolts), and the Russian Empire (this world's leader in submarine technology) had no reason to sell their colony in Alaska. Tensions along the Alaskan/Canadian border are perpetually high, based on real historical tensions between the Russians and British at this point in time. Germany and Japan are rising powers, not too unlike their real counterparts, albeit with more advanced technology. The Tesla of this Earth is employed by the Austro-Hungarian Empire to design electrical and chemical weapons.

Another major shift on the American continent is that the various Native tribes, whose lands in the western regions have been threatened by the Union and the Confederacy, have become far more united than their historical counterparts. Rather than waiting to fight the American governments piecemeal, the tribes have become closer and better organized as well as having modern automatic weapons and similar technology. If a western push were to be attempted, it would be far more difficult and bloody than our version.

It's unclear if any counterparts of the late 19th century wars or a looming equivalent of the Great War might be on the horizon, as the books don't go into a lot of political analysis. It's mentioned that the Japanese fought some colonial wars in Asia with the British and other powers, but they seem to be smaller in scale than a conflict like the Russo-Japanese War. But it's an interesting take on alternate history and there's a lot of possibilities in such a setting.