Surrenders depend on alot of factors i think.
I was playing as an evil human empire, with me in this large galaxy were the Torians, Terran Alliance, Drengin, Dratha, Krox, Alterians and Yor.
The Dratha became very powerful very quickly, they had a huge empire in the middle of the map i was stuck in one corner with quite a nice little empire, the Drath took out the Yor and 4 minor civs quickly, and while i was attempting to build an invasion fleet to take out the Terran Alliance the Dratha declared war on me.
I quickly moved my forces to intercept their fleets but i realised they wernt alone, they were allied to the Torians and Alterians, while those two didnt declare war on me i checked and the "Goody Two-Shoes Club" were at war with the Drengin and Krox, and i was doing all my trade with those two empires.
I realised i'd have to do something to help the evil empires of the galaxy before they got wiped out and i got left with no one to trade with.
After alot of effort and tech tradeing i allied myself with both the Drengin and Krox, the wars tailed off ,maybe because we were allied... i dont know... anyway eventually everyone was at peace.
Then the Torians decided to stick their oar in, 15 miliseconds later the theres a galaxy wide war going on i was taking on the Dratha alone they were the most powerful empire,but i gradually started to make some headway, the Alterians were stuck between the Krox and Drengin so were under attack from two sides.... the Torians who had started this fight were hiding behind the Terran Alliance, and they were the least powerful empire in the galaxy...and they started it *sigh*
After 20 or so years of non stop war the Evil Alliance is starting to win, the Dratha's navy is mostly wreackage and the Alterians are losing world after world to the Drengin/Krox (while the torians send small fleets to annoy everyone else.) Then the Alterians Surrender...
"We can no longer participate in this galaxy wide war, we hand our worlds to our steadfast ally the Dratha, and hope they can end this reign of darkness that has engulfed us all" (something along those lines anyway...)
Now that is what i consider cool, the Alterians surrendered.. ok.. but they surrendered to their allies the Dratha, and also made mention of the fact they had been at war for along time with a number of evil empires, it just made me grin when i saw that.