I know that one way to make phosgene is to make chloroform first, and then to leave it in the sun for some time with access to oxygen. Is this the way phosgene was made during WW1?

From what I've read, John Davy discovered it after he mixed carbon monoxide and cholorine and exposed the mixture to sunlight. Also, would mixture be the right term, or would it make more sense to say solution? Do you use the same terminology for gasses as you do liquids, since they're both fluids? I'm very new to chemistry.