"It seemed like no force in the world could slow J.P. Morgan's drive to power. In the summer of 1901, the financier was assembling his next mega-deal: Northern Securities, an enterprise that would affirm his dominance in America's most important industry: the railroads. Then, a bullet from an anarchist's gun put an end to the business-friendly presidency of William McKinley. A new chief executive bounded into office: Theodore Roosevelt. He was convinced...