contend vs join battle

contend and join battle both are verbs.

Word	Noun	Adjective	Verb	Adverb
contend	No	No	Yes	No
join battle	No	No	Yes	No

As verbs, join battle is a hyponym of contend; that is, join battle is a word with a more specific, narrower meaning than contend:

contend (verb)	join battle (verb)
to make the subject of dispute, contention, or litigation	engage in a conflict
have an argument about something
maintain or assert
compete for something; engage in a contest; measure oneself against others
be engaged in a fight; carry on a fight
succeed in doing, achieving, or producing (something) with the limited or inadequate means available