The Munitions of War Act 1915 prevented the resignation of munitions workers without their employer's consent. It was a recognition that the whole economy would have to be mobilised for the war effort if the Allies were to prevail on the Western Front. Supplies and factories in British Commonwealth countries, particularly Canada, were reorganised under the Imperial Munitions Board, to supply adequate shells and other materiel for the remainder of the war. The Health of Munitions Workers Committee, one of the first investigations into occupational safety and health, was set up in 1915 to improve productivity in factories.