I'm interested in how warfare evolved from ancient times to the modern day - tactics, equipment, training, etc. Are there any good books on the subject?
While it does not cover everything one might desire, as a thoughtful overview that puts the changes into a broader narrative, Keegan's A History of Warfare may be what you are looking for. It's an interesting read.
Richard Rhodes “The Making of the Atomic Bomb” does an excellent job detailing how war changed from the civil war through the end of WW2 and into the Cold War.