WARNING: The following article contains spoilers from War for Earth-3 #2, on sale now.
Amanda Waller has successfully conquered Earth-3 in the War for Earth-3 #2 (by Robbie Thompson, Dennis Hopeless, Kieran McKeown, Dexter Vines, Ariel Olivetti, Julio Ferreira, Brent Peeples, Matt Herms, Simon Bowland). Not only did she force the Titans into a tactical retreat, but she successfully manipulated Rick Flag and the Suicide Squad into giving her exactly what she needed to win. So once again, Waller has proven herself to be a world-class manipulator, capable of toppling the most powerful men and women of the day with nothing but her wits.
Despite this victory, it is also a symbolic defeat for her. Waller has made Earth-3 her priority but has elected to "save" this world because every time she's tried to do so in her world, she failed. It is essentially Waller giving up on her home because it was too hard to protect, despite all the time and effort she has put into it. So while she won, this is also her admitting defeat.
Despite her brutal methods, Waller is a protector. Everything she has ever done has been in defense of something she cares about, be it her family or her country. It's why she revived the Task Force X program, to turn something negative into a tool. For all her efforts, though, Waller has never truly achieved the security she wanted for her home. All the victories the Suicide Squad had won for her have not amounted to anything in the long run, just a series of temporary wins to stave off the chaos.
She's tired of having to fight tooth and nail just to see tomorrow and then repeat the process all over again. The restructuring of the multiverse, however, provided an out. Her world simply refused to be saved, so she would move on to a world that would adhere to her methods. Earth-3 was, of course, the perfect target.
Being a world that obeyed brutality on a daily basis, Waller's methods would be incredibly effective. The best part of it all was that, in comparison, Waller's methods would actually be for defense rather than abuse. She may still rule the world, but she would do so as a more "benevolent" dictator. It wouldn't even be that hard. Earth-3 was hardly a bastion of unity before she showed up. The Crime Syndicate despises and distrusts one another. On top of that, they are a far cry from their predecessors. The latest Owlman is a confirmed idiot, and Superwoman's shifting loyalties meant there would never be a stable environment for them to work together in.
So, really, conquering Earth-3 was always going to be easy. Waller is a master at puppeteering some of the most dangerous men and women on the planet. In comparison, she was dealing with superpowered children here. At the same time, though, she only chose Earth-3 because it would be easier. The Crime Syndicate removed most of the competition early on. Any heroes that existed are either dead or too intimidated to fight back. It was an easier world to protect than Earth-0, and one that she could be relatively sure would never slip from her grasp. In the process, she has given up on her home and the people there and admitted that she failed to fulfill her personal mission. If she can do that to the universe she was born in, how long will she be willing to keep Earth-3 "safe" once things become difficult again.