Who is Messengers (from The Phoenician Women) from Euripides V and what is their importance?

The messengers from The Phoenician Women bring information about the Thebian and Argive conflict. The first messenger tells Jocasta of the battle between the armies and informs her that Polyneices and Eteocles plan to fight to the death. The second messenger informs Creon of the fight between Polyneices and Eteocles, and the deaths of the brothers, as well as their mother Jocasta.