Sailing on the Chesapeake Bay's myriad inlets in summer, it is hard to imagine that come January icebreakers might be plowing the waters you cruised in July.When portions of the Great Shellfish Bay are iced up the flow of commerce is impeded. At the turn of the 19th century, with the center of the new nation's government established in its arms, a frozen Bay meant that the United States' emergence to a status on par with the foremost nations of the world might be painfully slow. Throughout the 20th century years of extreme cold continued to halt navigation and fishing. James Foster chronicles the disasters, large and small, which come with the coldest of winters.