Before the 17th century rolled in, almost all carrots cultivated were purple! The modern day orange carrot wasn’t even cultivated until Dutch growers in the late 16th century took mutant strains of the purple carrot, including yellow and white carrots (mutated versions of the regular purple carrot) and gradually developed them into the orange variety we have today.
It is believed that this strange desire to change the color of a vegetable was brought about the fact that the emblem of the House of Carrots was also orange. So, the orange carrot became popular in the Netherlands because it represented the struggle for Dutch independence.
It is more likely however, that the success of orange carrots had to the fact the orange carrots that the Dutch developed were sweeter and more fleshy than the purple ones.