However, it wasn't a failure at all. I didn't realize this for some time, but the Great Work prevented Constantinople from flipping over to Babylon.
I decided to use my Music Artist for a Great Work here. It'll much help to push the borders back and gain quicker access to these cities I want to capture, plus skip a few turns of resistance. And if I do decide to go cultural, Constantinople is definitely one of the legendaries - it's a holy city and can work about 12 cottages.
The Great Work claimed a total of no tiles that I wanted. However, it wasn't a failure at all. I didn't realize this for some time, but the Great Work prevented Constantinople from flipping over to Babylon.
At least I followed it up by recapturing Moscow, though the RNG screwed me again when three consecutive 83% catapults all died.
I had not managed to explore past Sitting Bull's territory, thanks to the earlier war that left him mad enough for no Open Borders. I declared war in order to get a scouting workboat past his water, only to discover that HE had a workboat blocking mine! That delayed my boat long enough for a Bull galley to kill it.
I then had another RNG bullshit moment. Sitting Bull brought one spearman and one archer. They got next to Constantinople on a forest tile. I had one vulture on defense. The spearman attacked at 9% odds and won four out of six rounds. And the archer captured the city. Then I even lost an HA at 76% trying to recapture it. Bullshit. And for some bizarre reason, the city did not reclaim its borders on the recapture turn, so it even starved.
Wow, this game is just full of unusual tactical situations. Sitting Bull mustered another stack to go after my city. I pulled all my units (capital has been cranking fresh catapults) into Moscow to hit it with siege. Except... that the stack just sat there on the forest instead. Bull lacked Open Borders with France and now could not reach me!
However, I can't go after France now - capturing Paris would expose Moscow to Bull's stack!
So I hatched this plan. I sent a worker up towards Sitting Bull, hiding in Persian territory until Bull would talk peace. At the right moment, I moved the worker as indicated in the picture, and the peace treaty got him kicked out to the far side of Native American territory. :) However, that was all for naught as there were no more civs to contact beyond Bull. The remaining five must be on an island somewhere, which I pretty much already knew from the oddly disabled domination win condition.
Anyway, the next mole to whack was Paris. Total cost was one catapult even for the hill city. Bullshit swung back in my favor when catapults won at 11% and 36%. Paris got razed; it holds no wonders or anything important or any helpful tiles.
I bypassed Babylon for now, because he's been at war with Boudica, who attacked him but failed badly, and now there are about seven CG2 bowmen in Babylon.
Since I'm putting on a tactics clinic here (when I'm not screwing up and undercommitting one too few horse archers), here's another example. This is one turn after Paris was razed. Mutal's borders have not adjusted yet. Right now Maya control extends only to the thick cyan line. But at end of turn, it will jump out to the thin line.
By moving the catapults as indicated right now and declaring war this turn, I basically get to begin the war two tiles into enemy territory. The catapults are still damaged right now, but I just got my GG for a medic, and one turn of healing will suffice.
Also, there just happens to be a Mayan archer outside the city (SE of Mutal), and the marked horse can kill it and rejoin the catapult stack.
Mutal fell with another total loss tally of 1 catapult, the RNG helping with 3/4 retreats all around 50%. Temple of Artemis and the Hindu shrine means it's a keeper.
And then I pulled the same move-before-borders-adjust trick on Madrid. Complete with catching an archer off guard outside the city. 2 catapult losses and Madrid the triple holy city was mine.
The alert reader will notice that I positioned correctly at Madrid to do the same thing to Persepolis.
The Persepolis fight lasted some time, though. Cyrus had up to 10 units on defense. I had to kill the city in two rounds, first redlining with the catapults and killing one batch of units, then letting my "body" (non-siege) units heal for a turn and do it again.
I kept Persepolis, since it was well developed with Hanging Gardens and Great Wall and Scotland Yard and an academy. But that was a mistake. It's within third-ring culture of all of the Aztec, Indian, and Native American capitals, doomed to flip. It couldn't even work any tiles; all I could do with it was whip its population into units. Cyrus still had another city, but I just made peace, taking Currency.
I wanted to stop conquering now - now the AI unit stacks are getting seriously big. But I had to go for one more at Tenochtitlan. Otherwise Mutal is doomed to flip; it's already had one Aztec revolt. Monty does have a lot of units, but they're mostly jaguar fodder for my vultures and horses. He has no metal so no spearmen. Also razing Tenoch gives me control of the silver.
Sitting Bull on the other hand does have metal and the Protective trait. No go there. Madrid is within flip range of Cahokia - my plan there is to let it flip if it wants to, with horses ready to recapture it by force; after that Madrid cannot flip back again to Bull.