Qualitatively the worked single-user scenario realizing one of battles of the American-Mexican war. It is entrusted to you by command of the American soldiers. In it destruction of all hostile units and constructions will be your main objective. Besides, you should save the fort which is exposed to furious attacks of Mexicans in inviolability.
Copy the age3scn-file in the directory my documents \\My Games \\Age of Empires 3 \\Scenario. Launch game and select the desirable scenario from the Single Player — Custom Scenario menu.