After a fire destroyed the main rolling mill in 1857, Newkirk persuaded his co-investors to rebuild it on a larger scale.

[7] The company grew rapidly and by the 1870s, was a leading producer of steel and an innovator in the advancement of steelmaking technology.

It performed early experiments with the Kelly converter, built the first blooming mill, and was one of the first plants to use hydraulics for the movement of ingots.

[6] The company was at its height in the 1870s, under the long-term leadership of general manager Daniel Johnson Morrell, who had overseen the expansion of the works into one of the largest producers of rails in the United States.

Morrell became concerned about the South Fork Dam, which formed Lake Conemaugh above Johnstown and Cambria Iron Company's facilities.

Morrell campaigned to club officials to improve the dam, which he had inspected by his own engineers and by those of the Pennsylvania Railroad.

Morrell offered to effect repairs, partially at his own expense, but was rejected by club president Benjamin F. Ruff.

The flood killed more than 2,200 people—then the largest disaster in U.S. history—and badly damaged the Cambria Iron Company's facilities along the rivers.