In the nineteenth century, the enterprise was in full expansion. François de Wendel (1774-1825) and Charles de Wendel (1809-1870) consolidated the prosperity of the factories. François, in Hayange, bought the forges in Moyeuvre and Jamailles which he set about developing. With him started the Wendels' political involvement; he was député, President of the Conseil Général on the Moselle département. Charles, with his brother in law, Baron Théodore de Gargan, founded the city and forges of Stiring Wendel. He bought the coalmines in Petite Rosselle, which allowed him finally to possess the raw material necessary to feed the smelting furnaces, thus cumulating coal mines, iron mines and forges.
Charles was also at the origin of the Wendels' social policies; he created a workers' town, hierarchical and dominated by the presence of both management and factories that remained a model until the 1930's. This enlightened employer understood the importance of the railway very early, and he founded a network intended to connect the factories to one another and to that of the Compagnie des chemin de fer de l'Est.