I'll probably replay the board to see if I can win pre-modern - generally I'm pretty bad at early warfare and I need to improve.
I decided that replaying the board was boring, so I played a new game with the same setting (Bismarck, immortal, raging barbs, pangea, promotion saving, although I did enable quick combat). I finished in 185 turns, which is still a lot worse than the best results here, but a lot better than 302. Probably in future I should stop building units once I have sufficiently overwhelming forces, to save myself from the sheer tedium of positioning all those units. 1 upt has some advantages, but manoeuvring large armies is certainly not compelling game-play.