Tulips Shall Grow (1942)

A young boy and girl, dressed in costumes based on Dutch traditional clothes, find their idyllic, windmill-laden countryside is being over-run by unfeeling, unthinking mechanical men that lay waste to everything in their path. The cartoon (note the title) was a very thinly veiled propaganda film in support of the Netherlands resistance fighters during Nazi occupation in World War 2 (The film was completed when Nazi Germany had completely occupied the Netherlands).