The Demons had full control over the Angel World. Nobody left without their say so. All gateways that were known were guarded while a steady stream of impure Angels constantly went through the Gateways to the Demon World. It was a one sided and uncontested harvest. However, the Demons were not counting on resistance, not heavy resistance anyway. What occurred next took them by complete surprise, as they were convinced that the Humans could not afford to intervene, if they even wanted to, with the Angels having been neutral in the Human - Demon War.
A Gateway leading to the Human World, southern parts of the Salynean Forest, lit up as the 6 guards looked over their shoulders at the activity. They were all pretty confused, unsure what this meant. Several seconds nothing happened, utter silence overtaking the beautiful world around them, even nature itself holding its breath. Finally, the first newcomer came through the gate. A Battle Droid. It recognized the 6 guards, identified them as Demons and marked them as hostile within less than a second time. Almost instantly after it came out, it locked on and opened fire, before another droid came through the gateway. And another. And another one. The 6 guards had no chance and were overwhelmed, 3 being killed on instant, while the other 3 tried to fight back, but were met with constantly growing barrage of blaster fire.
With the Gateway now relatively secure, the droids started to set up a perimeter. Control post was being established, the heavier equipment came through. First the full battalion of Battle Droids was through before the AAT's and Vulture Droids started to be transported through. While the unsuspecting Demons were proceeding with the operation, Eleanor, who had come to the Angel World herself, looked at what they'd established already. A battle ready command center, barracks for the human crew they had and a secure defense perimeter with AAT's functioning as defensive turrets, and Vulture Droids prepping for scouting runs. They'd stick out like a sore thumb in the skies, since they'd be the only flying objects other than birds. Eleanor nodded with approval, as she walked over the grassfields towards the command center. Their time had come. The Human Republic was indecisive and failed in everything. We lost many good people to the Demons in the last war. These droids would change that completely. She just hoped her friends on the home front could convince the Senate to not start a civil war. She would fight it to the end, but it wouldn't help them at all. Nor is it what she wanted.