With the war came the need for information and propaganda films. John and Joy recognised that animation could play a major part in this field, and with the encouragement of John Grierson, the founder of the documentary film movement, they founded Halas and Batchelor Cartoon Films. The partnership was further cemented when they married in 1940.

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By 1950, the studio had made over 100 films, such as Dustbin Parade 1941, in which a brave bone leads his rag and scrap metal friends to help with the war effort and the Abu series 1943, made in Arabic featuring a small boy named Abu and his donkey, facing fascism. The unit also made two feature length training films, 

Handling Ships 1945 and Water for Fire Fighting 1948.