Much of what fueled the growth of industry was the war itself. At one time the Union had over one million men in the armed forces--all of these men needed to be equipped and armed, and due to interchangeable parts and textile machinery, the North could do that. Also, the North won the war due to its ability to harness its rail system. After the war, this machinery did not die; rather, it was converted to civilian use. Telegraphs used during the war to call for reinforcements were used to order goods to factories or to place orders. The rail system made it possible for the same goods bought in Boston to be bought in Council Bluffs. Another thing that led to the growth of industry was the efficiency of the monopoly system run by such men as Carnegie and Rockefeller. While today's consumers want and need choices, Carnegie and Rockefeller were able to further develop efficient ways of producing steel and oil, respectively. Steel and oil also led to improvements in building, heating, and eventually transportation. Another thing that led to the growth of industry was increased immigration from Europe after the Civil War. Some of this was due to conditions in America, such as promises of cheap land, but a lot of it was due to conditions in Europe, such as the freeing of the serfs in Russia. With new labor pools also coming from the southeastern United States, there was no shortage of cheap labor to be had for one's factory.