He took advantage of the civil war to transform the Etna Works into one of New York's leading manufacturers of marine steam engines.

John Roach emigrated from Ireland to the United States in 1832 at the age of sixteen, eventually obtaining employment as a common laborer at the Howell Works of James P. Allaire at an initial wage of 25c a day.

[1] By the 1850s, Roach, concerned about the needs of a growing family and anxious to obtain a more secure financial future, began to consider starting his own business.

[2] In April 1852, Roach and his three partners purchased for the sum of $4,700 ($172,133) a small New York ironworks known as the Etna Iron Works, which had recently fallen into receivership.

[5] Roach was able to continue expanding the business through the sale of a variety of products, including Franklin stoves, firebacks, slats for iron shutters and other items.

[6] On September 2, 1859, the forced-draft boiler for the Etna Works' furnace exploded after accidentally being allowed to run dry, killing one man and seriously injuring two others, and gutting the building in which it stood.

The contract called for a bridge with a pivoting center section which could be rotated to allow large ships to pass through one of two channels beneath.

[8] The bridge that was eventually constructed was 526 feet (160 m) long, with masonry foundations, a cast-and-wrought iron superstructure, and a 216-foot (66 m) steam-powered pivoting center section spanning two 80-foot-long (24 m) ship channels.

Competition in the industry was fierce, and entry difficult due to high capital costs, but Roach believed that by utilization of the best tools, labor-saving devices and practices, he could compete successfully.

[10] When the American Civil War broke out in 1861, Roach was thus already well prepared to take advantage of the huge demand for marine engines generated by the conflict.

At its wartime peak, the Etna Iron Works employed almost 2,000 workers and was valued at $150,000, putting it in the front rank of New York's engine builders.

More importantly for Roach however, he realized that the government was planning to modernize its own shipyards, and he made a timely shift into the manufacture of machine tools in 1866.

He was keen to establish a plant with direct water frontage, which would both save him the cost of transporting his engines to the docks, and also enable him to move into the potentially lucrative business of ship repair.

The obvious target for acquisition was the Morgan Iron Works, a leading ironworks with frontage on the East River, and which like most other marine engineering plants had lain mostly idle since the Civil War.

Fortuitously for Roach, the proprietor, shipping magnate Charles Morgan, had recently experienced a setback in his own business dealings, as a result of which he was short of capital.

The Etna Works continued to operate as a general ironworks under new management until about 1881, when inventor Thomas Edison relocated production for his electrical illumination utility there.

In that year, the Roach family business sold the premises, the Edison having moved their expanding Machine Works to a much larger site in Schenectady, NY.