it's called The Lives of the Great Composers, here's a link to the amazon: http://www.amazon.com/Lives-Great-Composers-Harold-Schonberg/dp/0393038572
it's definitely a fun read, I'm only about halfway through it and I feel like it gives a pretty good summary of the lives of the early/really established musicians (bach, haydn, mozart, beethoven, etc.) I'm only just now getting into the sections where it's talking about multiple people per chapter, but he still does a pretty good job of describing them. I think the awesomest part to me is the early parts until it starts going into the mindset of beethoven and how big of a shift it caused. I won't spoil it if you want to read it but it's pretty awesome to see