With the onset of World War II, Cassandre served in the French army until the fall of France. His business long gone, he survived by creating stage sets and costumes for the theatre, something he had dabbled in during the 1930s.[7] After the war, he continued this line of work while also returning to easel painting. He worked with several famous French fashion houses, designing playing cards and scarfs for Hermès [8] and the well-known Yves Saint Laurent logo.