Ok, here's my end-game strategy:
1) Have a period of peace. Get wallstreet, oxford, and other infrastructure in place.
ERROR!
you had the troops, you were not backwards. Why wait?
2) Tech: Rifling-artillery-electricity-fission-rocketry
Steel was more than you needed at this point.
I would have build a few (2/3) galleons, a few more (4/5/6) frigates, and gone for the rest of cathy, then for ragnar while he was at war with memehd (or bribed memehd for a war a few (5/6) turns before my small fleet was in range. If Ragnar's navy was better than the 5/6 frigates you had, you could have built some more then upgraded to destroyers.
Combustion is the way to go. I go straight to railroads for MGs. Who needs artillery when the enemy doesn't have MGs? canons are good enough.
right! way to go!3) Try and generate at least 1 GM for upgrading siege to cannons or better artillery if possible.
After liberalism, I find GM > GS.
3000 gold > 1800 beakers!
4) While manhattan project is building, go to war against issy with sole objective of securing her sources of uranium (I think she has around 3, I have two). Depending on how many sources of uranium exist on other continent, I may consider sending a force over there as well, not sure. Would prefer to keep them busy with each other.
nukes come too late.
canons come right when you need them or better said, as soon as you have canons, you can just build those + a few defensive units and go for the rest of the world.
I have a smile on my face when I think about MM having assembly line, and me only steel... a few turns later I had a pretty good vassal

5) Once manhattan project is built, use mass nukes to finish Issy off.
$ rushing nukes can be good, but it's soooo late.
I've never used nukes before and I want to try them out. I might be able to win faster if I attack her outright earlier, but this will be more fun![]()
or you die
