I read again the Historical background of this scenario: “Gelon's raiders captured a message providing the date of arrival of a body of Greek cavalry reinforcing Hamilcar's army. A treacherous plan was hatched to substitute Gelon's own cavalry for these reinforcements. At dawn on the specified day, Gelon's horsemen entered the Punic sea-camp without raising any suspicion. They suddenly attacked, raising havoc and killing Hamilcar”.

I think that the author’s intention was precisely to allow that the Syracusan player tried to kill Hamilcar on his first turn (Hamilcar, in effect, is alone during the first turn!)
This option is possible only if the medium cavalry in G9 hex is the Syracusan unit.
And then Eumachus is the name of Syracusan Leader, not Chartaginian Leader.
Finally, if medium cavalry with leader in G9 hex is a Chartaginian unit, the scenario is tilted in favor of Chartaginina player.
So I believe the medium cavalry in G9 should be a Syracusan unit.
What do You think about my opinion?
Sorry if I bored You and sorry for my very bad English.
Andrea

You are correct. The cavalry unit and the leader are Greek blocks. It has been covered at sometime long ago in the errata I think.

Hi guys,
I've just received an official answer from Mr Anthony Curtis (GMT GAMES):
Eumachus is Syracusan. The battle opened with a surprise attack by Eumachus and his force inside the Carthaginian camp. The set-up is correct.
I've fixed scenario image according to this.