TISCO was able to expand steel production during the First World War because the British imports of iron and steel into India declined and the market for the steel manufactured by it increased. During the war, the steel produced in Britain had to meet the demands of the war. As a result, the imports of British steel into India declined dramatically. At this time, the Indian Railways turned to TISCO for the supply of rails. As the war dragged on for several years, TISCO had to produce shells and carriage wheels for the war. To meet the demands of the war, TISCO had to expand its capacity and extend the size of its factory. By 1919, the colonial government was buying 90 per cent of the steel manufactured by TISCO.