Incorporated in 1928 and operational by 1930, DOSCO was predated by the British Empire Steel Corporation (BESCO), which was a merger of the Dominion Coal Company, the Dominion Iron and Steel Company and the Nova Scotia Steel Company. DOSCO was one of the largest private employers in Canada during the 1930s-1950s. In 1957, DOSCO was purchased as a subsidiary of A.V. Roe Canada Ltd. and was later assumed in 1962 by Hawker Siddeley Canada. The company was dissolved in 1968 after the majority of its coal mining and steel mill industrial assets in Industrial Cape Breton were expropriated and nationalized by the federal and provincial governments.