Cecelia Holland 
Jack [EPUB ebook] 

Sixteen year old Jenny Dolf hates being a girl. She resents the restrictions on her life, and she just feels wrong, and trapped, in her female’s body. When the Revolution breaks out, she takes her father’s musket and poses as a boy named Jack, to join George Washington’s army on the heights of Long Island. From the first terrible losses, to the great victory at Trenton, in savage battles and long hard marches, Jack learns the value, and the cost, of freedom.