The title of this story refers to the real life Battle of Marathon which took place in 490 BC, during the first Persian invasion of Greece. The invasion was first attempt by Persia, under King Darius I, to subjugate Greece. The Greek army decisively defeated the more numerous Persians however and Rucka alludes to this as the Amazons too face seemingly overwhelming numbers of OMACs intent on wiping out the entire Amazon race.
After the attack by Cheetah, the Hague Court tells Diana that she is confined to her quarters until her trial. But when live TV reports show that Themyscira is under devastating attack by every last OMAC on the planet, Diana decides she has no choice but to break her word and rush to the aide of her sisters. She bids farewell to Rachel Keast who pleads with her not to go, knowing that this will effectively kill Wonder Woman’s reputation and her mission for ever.
As the U.S. Navy watch from off shore, Amazons are slaughtered as Io rushes to finish building the “doomsday” weapon. Diana arrives just in time to save Artemis from being killed and draws the attention of all the OMACs to her as Io finally finishes the device. As Artemis prepares to use it Diana is seemingly finally overwhelmed by her hundreds of attackers…