defend

argue or speak in defense of; "She supported the motion to strike"

be on the defensive; act against an attack

protect against a challenge or attack; "Hold that position behind the trees!"; "Hold the bridge against the enemy's attacks"

fight against or resist strongly; "The senator said he would oppose the bill"; "Don't fight it!"

protect or fight for as a champion

be the defense counsel for someone in a trial; "Ms. Smith will represent the defendant"

state or assert; "He maintained his innocence"