They were not even willing to come to the Alien Planet.
The aristocrats who truly wanted to join the war on the Alien Planet were mostly those whose family fortunes had declined or were on the verge of extinction, just like Ji Xinghe's first captive, who sought to restore their family's glory by distinguishing themselves in battle.
Or, their families were simply too large, with the patriarch, the highest ranking ape, having too many offspring and not enough territories or titles to bestow upon them.
Either the strong ones in the family joined the battle to secure more resources through their achievements to satisfy these young apes, or they let the less favored ones go to the battlefield to gain their honors.
The first captured mecha weapon with special features, the Chain Saw-tooth Knife, came from such a young ape of an imperial noble family.
Of course, there were also apes who were naturally combative and aspired to amass honor and achievements through wars.