Howard Fast 
The Unvanquished 

Originally published in 1942, The Unvanquished is the story of the Continental Army and George Washington in the desperate early months when the American Revolution faced defeat and disintegration. The book begins with the retreat across Manhattan“s East River that saved the Continental Army after the Battle of Long Island. It ends with Washington“s recrossing of the Delaware in the daring 1776 Christmas Eve raid on the Hessian camp at Trenton.