During the American Revolutionary War in 1775, Captain Benjamin Martin, a veteran of the French and Indian War and a widower with seven children, is called to Charleston to vote in the South Carolina General Assembly on a levy supporting the Continental Army. Fearing war against Great Britain, Benjamin abstains; the vote is nonetheless passed and, against his father's wishes, Benjamin's eldest son Gabriel joins the Continentals.
Two years later, Charleston falls to the British and a wounded Gabriel returns home carrying dispatches. The Martins care for both British and American wounded from a nearby battle, before British Dragoons, led by Colonel William Tavington, arrive, capture Gabriel with the intention of hanging him as a spy, and take captive the African American free men and women who work Benjamin's land. When Benjamin's second son Thomas tries to free Gabriel, he is shot and killed by Tavington, who then orders the Martins' house burned, and wounded Americans executed. After the British leave, Benjamin gives his next two eldest sons rifles, and they ambush the British unit escorting the captive Gabriel. Benjamin skillfully, yet brutally, kills many soldiers with his tomahawk. A British survivor tells Tavington of the attack, earning Benjamin the moniker of the "Ghost". Gabriel decides to rejoin the Continentals and Benjamin soon follows, leaving the younger children in the care of Benjamin's sister-in-law, Charlotte. On their way to the Continental Army's camp, they witness the southern Continental Army under General Horatio Gates engaging the British Army. Benjamin recognizes the foolishness of the action, having served in the British Army; sure enough, the Continentals are decisively routed.
Benjamin meets his former commanding officer, Colonel Harry Burwell, who makes him colonel of the local colonial militia due to his combat experience and also places Gabriel under Benjamin's command. Benjamin is tasked with keeping Lord Cornwallis's regiments pinned south through guerrilla warfare. French Major Jean Villeneuve helps train the militia and promises more French aid.
Gabriel asks why Villeneuve and others often mention Benjamin's role in something called "Fort Wilderness." Benjamin, having been hesitant to answer the question up to now, finally tells his son the story. Benjamin had been fighting in the British Army in the previous war when he and several other soldiers discovered a French atrocity at a fort that Benjamin and his comrades had been trying to reinforce. In a teutonic rage, Benjamin and his comrades caught up with the French at Fort Wilderness, where Benjamin and his unit literally cut the defending French soldiers apart slowly. Benjamin reveals that he has been haunted by guilt ever since.
