Zosimus is elected pope. Zosimus will become best known for playing a role in the controversy surrounding the Pelagian heresy. He doesn't handle matters very well, apparently giving too much credence to the defenses and arguments offered by Pelagian defenders, and thereby alienating many bishops in Africa who opposed the ideas of Pelagius.
In fact, the temper of temperment of Pope Zosimus was such that he had trouble effectively handling a number of other controversies as well. For example, he accepted a direct appeal from someone condemned by a bishop instead of letting the appeal go through the normal channels.