William Cockerill went to Belgium as a simple mechanic, and in 1799 constructed at Verviers the first wool-carding and wool-spinning machines on the continent. In 1807 he established a large machine workshop at Liege. Orders soon poured in on him from all over Europe, and he amassed a large fortune. In 1810 he was granted the rights of naturalization by Napoleon I, and in 1812 handed over the management of his business to his youngest son, John Cockerill (1790 - 1840). Thanks to his own energy and ability, aided by the influence of King William I of the Netherlands, John Cockerill largely extended his father's business. King William secured him a site at Seraing, where he built large works, including an iron-foundry and blast furnace. The construction of the Belgian railways in 1834 gave a great impetus to these works, branches of which had already been opened in France, Germany and Poland. In 1838 Cockerill met with a carriage accident which nearly proved fatal, and the prospect of his loss resulted in the credit of the firm being so badly shaken that in 1839 it was compelled to go into liquidation, the liabilities being estimated at 26 millions of francs, the assets at 18 millions. This reverse, however, was only temporary. John Cockerill had practically concluded negotiations to construct the Russian government railways, when his constitution, undermined by overwork, broke down.
William Cockerill had three sons and one dauther.