A polemarch (/ˈpɔːləˌmɑːrk/, from Ancient Greek: πολέμαρχος, polemarchos) was a senior military title in various ancient Greek city states (poleis). The title is composed out of the polemos (war) and archon (ruler/leader) and translates as "warleader" or "warlord", one of the nine archontes (ἄρχοντες) appointed annually in Athens. The name indicates that the polemarchos' original function was to command the army; presumably the office was created to take over this function from the king. Eventually military command was transferred to the strategoi (στρατηγοί), but the date and stages of the transfer are not clear. At Marathon in 490 BC the strategoi debated and voted on strategy, but Callimachus the polemarch had a casting vote, and he was the leader; it is disputed whether that means he was the real, or merely the titular commander-in-chief. Certainly the polemarchos no longer had military authority after 487/486 BC, when archontes were appointed by lot and it could not be expected that every polemarch would make a competent commander.
Thereafter the polemarch's main functions were legal. In the 4th Century BC, he had charge of trials of metics' family, inheritance, and status cases, and of the allocation to tribe-judges (members of the Forty) of other private actions involving metics; and it is likely that at an earlier period, his responsibilities for cases involving aliens were more extensive. He also conducted certain sacrifices and arranged the funeral ceremony for men killed in war.
The most famous polemarchos is probably the Athenian archōn polemarchos. He was of the magistrates called archons. Originally, the polemarch was a commander of the army, but after 487/486 BC, when the Athenian magistrates were appointed by lot, the military duties were handled by the strategoi. This office also had religious and legal functions.