Aristides was the son of Lysimachus, and a member of a family of moderate fortune. Of his early life, it is only told that he became a follower of the statesman Cleisthenes and sided with the aristocratic party in Athenian politics. He first came to notice as "strategos" in command of his native tribe Antiochis at the Battle of Marathon, and it was no doubt in consequence of the distinction which he then achieved that he was elected "archon eponymos" for the ensuing year (489488). Pursuing a conservative policy to maintain Athens as a land power, he was one of the chief opponents of the naval policy proposed by Themistocles.