What major accomplishments did ares do?

He didn't do any admirable deeds, if that is what you ask. He turned Alectryon, a youth supposed to guard Ares' door so that Helios would not find Ares in the process of loving Aphrodite, into a rooster because he fell asleep and Helios did discover them. Ares also fought with the Trojans against the Achaeans, but was injured.