In the final part of History Channel's four-part series (Part 1, Part 2, and Part 3 here) we see how these five men - John D. Rockefeller, Cornelius Vanderbilt, Andrew Carnegie, Henry Ford and J.P. Morgan - led the way from Civil War to the Great Depression and through to World War I. Whether for better or worse; for richer or poorer, in ethical and societal sickness or health, railroads, oil, steel and electricity had all been harnessed in less than 50 years, but the face of America was changing and would never be the same.