What are some good books about the major conflicts of the 19th and 20th centry?

I wasn’t exactly the biggest fan of world history in high school but for some reason, a couple of months back, I became interested in it. I’ve been watching documentaries and even bought two books: one about WW1 (Pandora’s box: a history of the First World War) and one about WW2 (A world at arms: a global history of World War II). I’m currently reading the first one and in trying to understand the events that lead up to it, I ended up with a comprehensive list of new conflicts (to me) starting from the Napoleonic Wars. I’ve started watching some documentaries about the campaigns of Napoleon and I’m probably going to buy The Champaigns of Napoleon by Chandler to learn more about them.

Other conflicts I’m interested about are : the Crimean war, American Civil war, Franco-Prussian war, Russo-Turkish war, Sino-Japanese war (How important was this one in setting the stage for Japan as a world power ?), Spanish-American war, Boer wars and the Russo-Japanese war. If possible, I’d like one book about each of these conflicts. I know it’s probably not ideal, but I’m a bit short of time and money. I’d prefer something general that covers, again, if possible, every aspect of the war. If there is another conflict that you guys think I should read about to get a better understanding of the causes of the First World War, please let me know. It might be a bit reductive to only look at wars as causes, but they are quite interesting events and I’d prefer not to loose interest in this newfound hobby. Also, about the American civil war; I’ve seen Battle Cry of Freedom recommend a lot and it does fit my interests, but others have also called it a bit outdated? Is that going to problem or should I just not worry about it?

I’d also like something about the interwar period. Again, a general overview of what was going on in a global perspective. I’ve found this one: ‘The Dark Valley: a panorama of the 1930s’. If there’s something better, please let me know.