As the First World War progressed, operating conditions in Europe became increasingly unstable. While some activities continued under difficult circumstances, the situation in Russia deteriorated rapidly.

From 1915 onwards, companies operating in the country were placed under state supervision as wartime priorities reshaped control over strategic industries and infrastructure. As conditions worsened, workers, fearing for their safety, were forced to leave the projects and flee to Sweden, with Stockholm serving as a key place of refuge, and operations in the region were gradually abandoned. For the DEME founders, whose activities in Russia and the Gulf of Finland relied on a specialized fleet of dredgers, pontoons, tugboats and support vessels, this marked a decisive loss of operational autonomy.

In 1917, the Russian Revolution led to one of the most dramatic moments in DEME’s history. On behalf of the Russian government, twelve vessels belonging to Ackermans & van Haaren, loaded with equipment, were convoyed to Saint Petersburg, where they fell into the hands of the Bolsheviks. In January 1919, the equipment was seized and nationalized, representing a substantial financial loss for the company.