Fort Dearborn was re-occupied on July 4, 1815. Mackinac was transferred to American hands on July 18, 1815. In the fall of the same year Colonel R. C. Nichols of the Eighth United States Infantry attempted to ascend the Mississippi to Rock Island, but was compelled to pass the winter in the vicinity of the mouth of the Des Moines River. On May 10, 1816, however, he reached Rock Island, where the construction of Fort Armstrong was undertaken. June 21st of the same year saw the re-occupation of the site of Fort McKay at Prairie du Chien; and Fort Crawford soon protected this important point at the junction of the Mississippi and Wisconsin rivers. One other point, vital in all western transportation was at the head of Green Bay at the mouth of the Fox River. Colonel John Miller of the Third Infantry arrived at this place on August 7, 1816, and soon began the erection of Fort Howard.[53] But the government was not content with these movements. In a report dated December 22, 1817, the Secretary of War, J. C. Calhoun, wrote to the House of Representatives that "a board of the most skilful officers in our service has been constituted to examine the whole line of our frontier, and to determine on the position and extent of works that may be necessary to the defence of the country."[54] Plans had already been made. During the summer of 1817 Major Stephen H. Long, a topographical engineer in the United States Army, had made a journey to the Falls of St. Anthony in a six-oared skiff and had approved the position at the mouth of the Minnesota River as a location for a fort.[55] Other plans were soon announced. In the spring of 1818 _The Washington City Gazette_ stated that a fort would be built on the Missouri River at the mouth of the Yellowstone River;[56] and a second report of the Secretary of War on December 11, 1818, indicated that the site at the mouth of the Minnesota would soon be occupied.[57]