EXTRA INFO:
He believed that among his earthly missions was to free the American slave
He also rallied others to join him and eventually the division of people who thought slavery was right and those who thought it was wrong became too strong.
ANSWER:
Brown's raid foreshadows the fact that a few years later a civil war breaks out between the north and south. It foreshadows it because he is fighting for what the union will fight later on.
(here is a two sentence answer)