At 500 AD, I was 1 turn away from meeting the Old World. As I met the AI on the continent, I didn't make any trades other than trading maps with the first AI I met (couldn't get negative diplo points if I didn't know the other AI yet).
As in most of the games mentioned here, there were two major camps: the Buddhist camp made up of Peter and Mao and the Jewish camp made up of Hatty, Napoleon and Mansa. I hate to depend on Peter or Mao for anything, so I decided very early to put my hat in the Jewish ring (soon to be Confucian ring...

).
Before I continue, I have to admit that I am one of those players who never really pays attention to the diplomatic situation during a game. I typically accept and refuse trades and demands based on how I'm feeling at the time, not based on the relationships of the other civs. With that said, this was new territory for me... let's call it "on-the-job training" or "trial by fire."
I had loaded a Confucian missionary on each of my caravels. I sent them both to a city of Mansa's and spread the good message of Mr. Confucius. Having never done this before, I saw that Mansa was now willing to switch to Confucianism for a cheap tech. Wow, this is going to be easier than I thought. What could possibly go wrong? I know, famous last words, right? Well, my big happy family wasnt so happy any more. I was getting Youve traded with our worst enemy modifiers from both Nappy and Hatty now.
After learning Astronomy, I did something that I would have never dreamed about a week ago; I set up a galley chain and began sending missionaries to the Old World. As quickly as I could, I converted Nappy and Hatty to Confucianism as well. We were all a big, happy family again!
About this time, I saw a great barb city on the eastern coast of the Old World that would make an excellent UN city, which could be gifted to either Mao or Peter to ensure that I wasnt up against one of my allies in the upcoming election. Just as I was about to load a few maces onto one of my galleys, Peter took the city.
Time for plan B. I unloaded my now useless maces and put a settler and worker in their place and set sail for the EL Islands. I plopped my settler down on L Island, founding Seattle. I then checked my trading options. Neither Mao nor Peter were willing to accept the city in trade I planned once the UN was built.

I should have known that they wouldnt want a city as rainy as Seattle. I should have changed the name before settling it. Well, maybe theyll like the city better once it has the UN in it
I started teching on the Mass Media beeline. I used Great Scientists to bulb Education, Printing Press, Physics and Electricity. I used Liberalism on Radio and the Great Artist from Music to bulb Mass Media, which I learned on T188 (1280 AD). I started building the United Nations in Seattle on T194 as soon as it had finished its forge first. I didnt finish the UN until T216 (1530 AD), almost 30 turns after finishing Mass Media. And this was with the help of a Great Engineer too! Boy, beelining Mass Media sure didnt do anything to speed up my finish date. It didnt help that I was building the UN in a new city with poor production, low population and very few forests.
I checked the trading screen again and Seattle was still not wanted by Peter or Mao. I could have built the UN in 5 or 6 turns in one of my main cities. Why did I go to all of the trouble of building the UN in a city that no one wanted?

Thinking back, neither Peter nor Mao had learned Astronomy, so this city wouldnt have been connected to their empire. I wonder if they would have taken it had they known this tech
Three turns before completing the UN, Hatty had switched back to Judaism and I started getting negative diplo points within my circle of friends. I started missionary spamming again in earnest (I had never stopped, but I now began focusing on Hatty only), spreading Confucianism to every one of her cities.
In any event, Peter was the largest civ, but not by much (Peter @ 77 vs. Mansa at 74). I won the Secretary General vote by a large margin even with Hatty not sharing my religion. I prayed that Mansa wouldnt outgrow Peter in the next several turns. I was finally able to get Hatty to switch back to Confucianism, three turns before winning the game in 1560 AD in another landslide vote.
I think I could have shaved quite a few turns off my finish date had I built the UN in one of my more mature cities. I also finished Oxford rather late (1210 AD), even though I prioritized Education (520 AD) over Astronomy. Finally, trying to spawn a Great Engineer at 100% odds meant that I never was able to crank up my GP Farm to generate all the Great Scientists I could have used to bulb more techs.
All in all, this was an interesting game and I'm happy to have won my first sloppy attempt at a diplo victory.