Louis Bamberger (1855-1944) was the epitome of the merchant prince as public benefactor. Born in Baltimore, this son of German immigrants built his business--the great, glamorous L. Bamberger & Co. department store in Newark, N.J.--into the sixth-largest department store in the country. A multimillionaire by middle age, he joined the elite circle of German Jews who owned Macy's, Bloomingdale's, and Filene's. Despite his vast wealth and local prominence,...