There's a book called War Lovers about how politicians like Teddy Roosevelt and Hearst worked together to drum up support for an expeditionary war against Spain.

There was also a book a few years ago called Confronting Imperialism that was a collection of essays on The Anti-Imperial League which opposed Hearst and Roosevelt's march to war. The members of the group included notable folks like Mark Twain, Andrew Carnegie (this is was one of the key events that pushed him to create the Carnegie Endowment for International Peace) and Helen Keller.