Following the American Declaration of Independence, communities from Boston to Savannah were forced to make a choice: to strike out for an independent republic, or remain true to the British Crown. This study explores the origins, methods and combat record of the combatants on both sides. The American Revolutionary War was America’s first civil war. As the conflict raged from Canada to the Caribbean and from India to Gibraltar, it was in American communities that the war was the most intimate, the most personal, and – accordingly – the most vicious. In 1775, the inhabitants of British America included those born in North America and newly arrived immigrants; the established landed aristocracy and the indigent; the diverse nations of the Native Americans; and people of African descent, both enslaved and free. The coming of war forced every person to make the choice of whether to side with the Patriots or remain loyal to the British Crown. With so many cross-cutting imperatives, the individual decisions made splintered communities, sometimes even households, turning neighbour against neighbour in an escalating spiral of ostracism, embargo, exile, raid, reprisal and counter-reprisal. Accordingly, the war on the frontiers and on the margins of conflict was as underhanded and ugly as any of the 21st century’s insurgencies. In this study, the origins, fighting methods and combat effectiveness of the combatants fighting on both sides are assessed, notably in three significant clashes of the American Revolutionary War.