JDR- Business Technique. Much as one might like to see John D. Rockefeller as the arch capitalist crushing competitors as he gained monopolistic power, it's not so (at least according to the biography I read). He did indeed control much of the oil in the United States but he was fair in the prices he offered competitors he wanted to buy out and he was modest in his personal expenses and generous in his charitable contributions all his life.
How he gain control
He was able to price his product so low that competitors couldn't compete. They would then go out of business and/or sell to JDR. Then JDR would jack his prices back up.
JDR also got control in the railroads so that you couldn't afford the transportation cost, where as JDR was getting a discount. JDR used lots of leverage in gaining his monopoly over oil. Tactics today would be criminal and stopped dead with lawsuits. But back in the golden era of American Business, the government didn't regulate anything and business ran wild.
Was John D. Rockefeller Robber Barron or Captian of Industry?
Rockefeller had to be ruthless in order to get what he got. However, he did have tremendous influence over the American business world of his time. I would have to say that he was both robber baron and captain of industry.
Rockefeller may have seemed to be a ruthless businessman to many but he has been one of America's greatest Philanthropists.
Mr. Rockefeller was the greatest businessman ever in my opinion. The companies he helped establish are still great investments to this day, Exxon (xom) and Conoco (cop) are excellent values in the stock market. Buy these stocks, you will make lots of money.
I don't think the two terms, "robber baron" and "captain of industry" are mutually exclusive. If you're making that distinction, you have to use a very tight definition of robber baron and a very liberal definition of captain of industry.