I'm currently playing as Terrans on an Immense map, normal difficulty, abundant everything with 8 opponents. I had the misfortune of starting next to the Krynn Consulate who were on a "war frenzy" at the time I met them. About 10 turns into our meeting, the Krynn declared war on me due to their much greater faction and military power relative to mine. At first they were able to destroy a few of my fleets, however as time wore on I could design the fleets to take on their ships quite easily. Eventually I was able to take 5 of their worlds through a combination of military and cultural conquest (most of their worlds have near-zero or zero approval due to Large Empire Penalty, while I have 97% approval), and am moving on to take more. Nevertheless the Krynn refuse to offer me reasonable peace terms and demand nearly all of my technologies to end a war that they are probably going to restart soon. Despite the fact that they are almost certainly going to be stripped of most of their worlds, they continue to fight.