blockhouse and stockade, built in 1803 because of Indian unrest, at a narrow bend in the Chicago River, northeastern Illinois, U.S., and named for Henry Dearborn, Revolutionary War hero. The fort was evacuated in 1812, but the garrison party was massacred by Potawatomi Indians just south along the Lake Michigan shore. The fort was burned but was rebuilt in 1816; it was abandoned in 1836. The site, marked by a plaque, is at the south end of the Michigan Avenue Bridge in Chicago.