California played a major role in terms of agriculture, industry, finance and propaganda during World War I. Its industrialized agriculture exported food to the Allies, 1914–1917, and expanded again when America entered the war in 1917. After the war ended, it shipped large quantities of food to central Europe as part of national relief efforts. Hollywood was thoroughly engaged, with feature films and training films. Attractive climate conditions led to the addition of numerous Army and Navy training camps and airfields. Construction of transports and warships boosted the economy of the Bay area.