The few years after 1900 were a great divide in the history of Cammell's; before World War I the company had been transformed. Charles Cammell and Company Ltd began the century as an important steel firm with plants in the Sheffield area and on the north-west coast; by 1910 it had disposed of the latter but had become a major shipbuilder. Development planning made the shipyard the focus of its activities. By this time the company also had important investments in the west Midlands and on Clydeside. Until 1901 it was led by Alexander Wilson, who had served under Charles Cammell, and who followed policies similar to those firmly established by his brother from the 1860s to the mid-1880s. Within eight years the company had already had two more chairmen who had come from outside the steel industry; by the end of 1910 the company was headed by a much younger man with no contact with an earlier tradition, and who was to lead the company through to World War II. Between 1900 and 1914 many traditional ways, and an established hierarchy of managers, were swept away in a remarkable series of dismissals and resignations.

Though not in the first rank in terms of size or capital, Cammell's now made wider extensions than its larger rivals. It already made armour-plate, gun forgings and some projectiles. Vickers and Armstrong's also made finished, heavy and lighter guns and had, at Barrow and Elswick, major naval yards. Armstrong's built its own armour-plate plant at Openshaw and the Clydebank yard had given John Brown a captive outlet for armour.