Ren Chartrand 
Forts of the American Revolution 1775-83 [PDF ebook] 

Though primarily fought in the field, the American Revolution saw fortifications play an important part in some of the key campaigns of the war. Field fortifications were developed around major towns including Boston, New York and Savannah, while the frontier forts at Stanwix, Niagara and Cumberland were to all be touched by the war. This book details all the types of fortification used throughout the conflict, the engineers on all sides who constructed and maintained them, and the actions fought around and over them.