Revolutions

A sample revolution screen where the player (German civilization) decides whether to pick Simón Bolívar (Peru) or José de San Martín (Argentina), and their respective bonuses.

European colonies have a new option open to them in the Industrial age; instead of advancing to the Imperial age, they can revolt from the home nation and establish their own country. The initial cost of revolting is cheaper than advancing to the Imperial age, but the nation's economy will stagnate because all settlers will turn into militia and no new ones can be built (except Coureur des Bois from a Cree Village). Resources can continue to be delivered from pre-constructed ships, tributed resources, trading posts, factories and for the Dutch, banks. A new nation may not upgrade units to the Imperial Age.

Stealth

Another new feature is the use of stealth. This enables certain units to remain undetected by most enemy units and buildings. All native civilizations have a unit that can use stealth (this cannot be activated when enemy units are nearby). For the Europeans, there are spies that can be sent from the home city or recruited from the church. Spies are particularly effective against explorers and war chiefs due to their bonus attack. They all share the stealth ability, as do other miscellaneous units (ninja, native scouts, etc.). When certain enemy soldiers are near the invisible unit, the unit will be revealed and vulnerable to attack. Stealth units also become visible when they attack.

Act 1: Fire

Nathaniel Black (loosely based on Joseph Louis Cook) is the half-Iroquois son of the late John Black from Act 2 in the previous game, raised by his mother Nonahkee and his uncle Kanyenke (Ká:nien in Definitive Edition). The campaign opens as Nathaniel and Kanyenke are trying to discourage the Mohawk and the Seneca from fighting in the American Revolutionary War. However, they are ambushed by a group of Mohawks and head to an Oneida village nearby. From there they counter-attack and destroy an enemy Town Center, thus causing their enemies to flee. When Nathaniel and Kanyenke return to their village, they find that the Mohawk and a group of Hessian mercenaries led by Colonel Sven Kuechler, have raided the village and captured Nonahkee. They rescue Nonahkee, but Kuechler and his main army escape, leaving the Iroquois Confederacy to dissolve. Nathaniel's village supports the colonists, and Nathaniel heads to Boston where his men help defend a redoubt on Breed's Hill from the British. After George Washington takes command, a series of defeats drives the colonials back across the Delaware, where they are joined by Nathaniel. Here, Washington leads a small force, including Nathaniel, across the Delaware where they attack a Hessian encampment at Trenton and defeat the rearguard of the army at Princeton. This is followed by another victory at the Battles of Saratoga. However, the army is once again defeated at Brandywine and Germantown and is forced to camp for the winter at Valley Forge, where they suffer greatly from the cold. This leads Nathaniel to use most of his family's fortune to supply the army throughout the winter. The next scenario is the fictional battle of Morristown, where Nathaniel has his chance for revenge on Kuechler, who leads an attempt to destroy the capitol building of Morristown. Using artillery shipments he receives from Washington, Nathaniel sneaks around the Hessian flank and relieves Morristown. Refusing to accept defeat, Kuechler joins the fight with Nathaniel and is killed. After Kuechler's death, Nathaniel is said to have fought at Charleston, Camden, and King's Mountain. As the tide begins to turn, the French join the war and help the revolutionaries gain a victory at Yorktown, where Nathaniel is instrumental in capturing several redoubts. With the Revolution won, Nathaniel returns home a poor man, having spent his family fortune on the war effort, but is memorialized as a hero after his death in 1812. During the epilogue video of the campaign, the "Old Coot" (secretly Morgan Black) from Acts 1 and 3 in the original campaign can be seen watching his great-grandson's victory at Yorktown.

Act 2: Shadow

In 1866, Chayton Black, Amelia Black's half-Lakota son whose father died when he was too young to remember, is expanding the Falcon Railroad Company westward along the Bozeman Trail but winds up in the middle of Red Cloud's War. He helps defend the wood trail from the Sioux and becomes friends with Fort Laramie's quartermaster, William "Billy" Holme, an aged American Civil War veteran. Ten years later, in 1876, Chayton returns to the west and again meets up with Holme, now a sheriff, who informs him of a gold rush in the Black Hills of Dakota. After defending many mining camps from Sioux attacks, Chayton goes to see the Sioux chief Crazy Horse and establish a peace treaty. However, Holme and some of the miners ambush the Sioux before Chayton can begin negotiations, wrecking any chance of peace. Despite the sheriff's warmongering, Chayton still sides with Holme and defends his workers as they gather wood for a new fort. However, once the fort is complete, Holme orders Chayton to destroy a Sioux village without provocation. Chayton refuses and, turning against Holme, allies with the Sioux to destroy the fort, forcing Holme to flee into the hills. Chayton then convinces the newly arrived George Armstrong Custer to give him one day to find Holme, who is the real cause of the unrest. Chayton puts on Sioux clothing and blood-red war paint and, joining with Crazy Horse, chases down Holme and corners him in a mine. Holme pulls a gun on Chayton, who draws his gun more quickly and shoots Holme, sending him stumbling into some gunpowder kegs and falling down a mineshaft to his explosive death. Chayton then tries convincing General Custer not to attack the Sioux, but Custer refuses and demands that Chayton choose sides, saying he can no longer remain neutral. Chayton agrees, bidding Custer goodbye and siding with the Sioux. He helps gather the Sioux and Cheyenne nations and fights with them at Little Bighorn. After the battle, Amelia Black narrates that she never saw her son again, but she has heard that Chayton was either killed at Wounded Knee in 1890, taking a dozen cavalrymen with him, or lived out his days in the Black Hills with his wife and children.

In Age of Empires III: Definitive Edition, Chayton's story is significantly revised, with he and Holme having fought alongside each other in the Civil War. Chayton's Sioux ancestry is also more focused on, his Lakota uncle "Frank" Warbonnet replaces both Amelia and Crazy Horse's roles, and all Native American enemies are replaced with outlaws.