THE BIG RED ONE was an unforgettable tragety that happened in the AETA. It happened a very long time ago, but what happened, was the Cats built a massive massive robot that was as big as the moon. 

They stole from Venus and took up almost all of the metal on it to make their robot. But, they made another stubborn attempt to make a SECOND

This infuriated The lion of death so much, so he sent both to a dog fight is the asteroid belt. The 2,000 pilots didn't question the orders, and flew out there, and both machines were destroyed.