My headline may sound either confusing or redundant; it's not.
Rabble In Arms is a classic novel, not about the Classical Age, but about the American Revolution. It comes out of that great period of American historical fiction - the 1930's and 40's - when such works were seriously researched and seriously intended.
The great thing about Rabble In Arms is that it is also a story well-told. There are Machiavellian plots and sub-plots, action sequences galore (several full-scale battles, by land and lake), full-blown romance(s) and plenty of humor, some of it wonderfully cantankerous.
The book is the second in Robert's series about the people of Arundel, in Maine (a real town; it's now called Kennebunkport) and how they lived through the formative years of the United States of America. Although it's not absolutely necessary - Rabble In Arms - stands well enough on its own - it would be good to read the first in the series, which is simply titled Arundel...first.
If you are interested in the American Revolution and you haven't read this book...you should do so as soon as possible. It contains a lot of things you need to know, and you can have a great time learning them.