The following contains spoilers for Trial of the Amazons #2, on sale now from DC Comics.
DC's latest Wonder Woman event kicked off by killing Diana's mother Hippolyta. The former queen of the Amazons had recently joined the Justice League and looked like she was becoming a bigger part of the DC Universe. Though it seems a different fate was planned for her. Up to now, the reason for her death has remained a mystery but the ending of "Trial of the Amazons" put everything into perspective.
Now that Trial of the Amazons #2 (by Becky Cloonan, Micheal W. Conrad, Vita Ayala, Stephanie Williams, Joëlle Jones, Elena Casagrande, Laura Braga, Skylar Patridge, Adriana Melo, Romulo Fajardo Jr., Jordie Bellaire, and Pat Brosseau) has brought the event to a close, the real reason for Hippolyta's death has become clear. It was previously revealed that Artemis, the '90s Wonder Woman replacement from Bana-Mighdall, was the killer. When asked, she remained silent as to why she resorted to murder. She didn't need to explain though, thanks to this climactic finale.
Before this event began, Artemis met with Hippolyta and two other conspirators, Diana's aunt Antiope and Bana-Mighdall's co-queen Atalanta. In this prequel story from Wonder Woman #781-784, "What Lies Beneath" (by Vita Ayala, Skylar Partridge, Romulo Fajardo Jr., and Becca Carey), Hippolyta and the others recruited Artemis to their unknown cause, claiming that what they planned was the only way to unite the Amazons. However, it would be disastrous. Now the disastrous consequences are in full view. The Amazons have been overrun by the might of the primordial Greek God Chaos, whom Wonder Woman sealed away during her time in the Godsphere. Despite how bad all of this destruction looks, it was ultimately for the best and explained why Hippolyta had to die.
By killing Hippolyta at the beginning of this event, Artemis and her fellow conspirators ensured that the Amazons wouldn't notice the threat of Chaos until it was too late. All the Amazons got caught up in their own personal battles instead, and the increasing tensions between the three tribes were pushed to their breaking point. Because of this, it was even more important that they all came together to fight against Chaos in the end. By amplifying every situation to its absolute worst, the four Amazonian conspirators ensured that their people emerged from this threat stronger than ever and finally united as one.
If Artemis hadn't killed Hippolyta, then the Amazons wouldn't have been distracted and the Themyscirans would have noticed Chaos emerging from Doom's Doorway. As such, they would have sealed the god away alone and never united with the Bana-Mighgdall and Esquecidas as they did here. Then, all three tribes would have gone their separate ways once again, remaining forever divided.
Antiope and Atalanta both sacrificed themselves to seal Chaos behind Doom's Doorway at the end of this issue. They took the place of whoever would have won the Trial of the Amazons and are now the defenders of the Doorway. This sacrifice also eliminated two more of the prequel's conspirators, leaving only Artemis to guard this secret from now on.
Artemis was sworn to secrecy, saying she would take the knowledge of this plot to her grave. She told Cassie and the other Amazons as much when her crime was found out. In all the confusion Chaos caused, she managed to escape and is now on the run, something which will be shown in the upcoming one-shot Artemis: Wanted #1 (also by Ayala and Partridge). However, if the real intentions of herself and Hippolyta weren't made clear here then it's likely this secret will never be revealed.
In the end, Hippolyta orchestrated her own death to make sure "Trial of the Amazons" would turn out exactly as it did here. Chaos may have caused much destruction across Themyscira, but this threat united the Amazons as one. It seems that the conspirators knew the risk in their plan, both during this event and in events to come, but decided it was for the best anyway. With only Artemis left standing, only she will be able to judge whether their actions were worth it, when the united Amazons face their next threat.