The continental army officer who worked closely with Washington and Lafayette and got killed in a counter attack was Baron Johann De Kalb.
B. Baron Johann De Kalb
Step-by-step explanation:
Johann Baron De Kalb was the military officer who served during the American Revolutionary War. It as in 1777 that he joined the continental army being impresses by the spirit of independence of the colonists. He was appointed as a major general by the influence of Lafayette.
He participated in the battle of Camden in which Horatio Gates was in command of the American regime. He was shot dead in the battle.