Why do some nations adopt command economies during wars?

During a war, some governments change their economic system from a market economy to a command economy.

aliens are not real, the myth was created about 700 years ago because people found markings in the field of their crops. also, no there were no aliens on the moon.

hope this ! give brainliest!

answer; the answer to the first question is (king james ii was replaced by his daughter mary and her dutch husband william of orange;