Although she initially forbids Diana to be trained as a warrior, Hippolyta reluctantly agrees to let General Antiope, Hippolyta's sister and Diana's aunt, train her, only more rigorously than any other warrior. In 1918, Diana, now a young woman, rescues US pilot Captain Steve Trevor when his plane crashes off the Themysciran coast. The island is soon invaded by German soldiers that had been pursuing Trevor. The Amazons kill the crew, but Antiope sacrifices herself to save Diana. Steve is interrogated with the Lasso of Hestia and reveals that a great war is consuming the outside world and that he is an Allied spy. He has stolen a notebook of the chief chemist Dr. Isabel Maru, who is attempting to engineer a deadlier form of mustard gas under the orders of General Erich Ludendorff from a weapon facility in the Ottoman Empire. Believing Ares to be responsible for the war, Diana arms herself with the "Godkiller" sword, the lasso, and armor before leaving Themyscira with Steve to locate and stop Ares for good.
The Crisis on Infinite Earths crossover of 1986 was designed and written with the purpose of streamlining most of DC's characters into one more-focused continuity and reinventing them for a new era, thus Wonder Woman and Steve Trevor were declared to come from the Earth-Two dimension, and along with all of their exploits, were erased from history, so that a new Wonder Woman character, story and timeline could take priority.
I remember when I read in the news that Wonder Woman had been cast and my heart sank ... I'm sure we wouldn't have made the same choice. And then I started paying attention to her, and watching her and looking at her and it was just unbelievable. Frankly, I think they did a better job than I could have because I don't know that I would have scoured the earth as hard to find her ... They were looking for all the same things I would have looked for—all the values that Wonder Woman stands for exuding from someone in an honest way, and boy did they find it ... She shares every quality with Wonder Woman and that's no joke. It's one of those rare things. You need someone who can appear to be Wonder Woman on screen ... Every once in a while, there's superhero casting that transcends, because that person is so authentic to the character that it becomes identified with them, like Lynda Carter or Christopher Reeve.
Having learnt of Wonder Woman's inability to return to Themyscira, Doctor Veronica Cale, a wealthy and powerful woman, set into motion a plan to use Wonder Woman to find Themyscira. Years earlier, Cale's daughter Izzy had her soul stolen by the gods Phobos and Deimos. They told Veronica that they would only return her daughter to her if she helped them find Wonder Woman, and got the location of Themyscira from her. Seeing no other option, Cale had formed a team called Godwatch, dedicated to locating Diana and Themyscira.