The Longstreet Society was locked out, then shooed away, as it tried to visit Chickamauga and Chattanooga National Military Park this weekend. Since Oct. 1, national parks and historic sites have been closed because of the federal government shutdown, the result of a budget showdown. But the Gainesville-based group, which seeks to preserve the memory of Civil War Lt. Gen. James Longstreet, was hoping against hope as it visited the site at the Georgia-Tennessee line as part of its two-day Sesquicentennial Seminar Series, scheduled long before the congressional squabble.