Advertising As an instrument of company trade policies, advertising underwent a lasting change during the World War. In August 1914 sales collapsed. Despite a partial recovery, sales figures were not to return to prewar levels before 1918. There were five reasons for advertising’s loss of importance. First, armament production came ever more strongly to the foreground, supplanting many heavily advertised consumer goods. Second, advertising was superfluous for many products. Some were scarce, so t…