After the entry of the U S. into WWII, many manufacturers such as the Firestone Tire and Rubber Company de-emphasized the sale of their products and services in their advertising campaigns in favor of demonstrating their support the war effort. Advertising was presented as an aid to help the public understand why some products were no longer available for purchase because the manufacturer was now producing war material (e.g., new washing machines were on hold as the manufacturer turned to producing war machinery).