war vs take the field

war is a noun but take the field is not a noun.

Word	Noun	Adjective	Verb	Adverb
war	Yes	No	Yes	No
take the field	No	No	Yes	No

war (noun)	take the field (noun)
the waging of armed conflict against an enemy
a concerted campaign to end something that is injurious
an active struggle between competing entities
a legal state created by a declaration of war and ended by official declaration during which the international rules of war apply

war (verb)	take the field (verb)
make or wage war	go on the playing field, of a football team
	go on a campaign; go off to war