Sentence:  Activity by British traders and the presence of a colony on the Red prompted the United State War Department in 1819 to send Lieutenant-Colonel Henry Leavenworth from <WSD>Detroit</WSD> to put a post 300 miles northwest of Prairie du Chien , until then the most advanced United States post . 
Meaning of the word marked with <WSD> tags:  the largest city in Michigan and a major Great Lakes port; center of the United States automobile industry; located in southeastern Michigan on the Detroit river across from Windsor