Well, the Sumerian war had what looked like an unfortunate happening:
So, I decided to have Greece declare war. During that period, though this happened, which made the above Persian capture look like a blessing in disguise:
Some Sumerian cities might flip in 20 turns, but oh well, I think.
Electricity cost a bit too:
Then we got the gold back via the ivory, sold/gifted Electricity to the other AIs, except Greece. Question comes as... after Greece, do I go at Persia and then the Byzantines? Or just wait until someone gets Replaceable Parts? I think just wait. The military advisor rates us average to Persia... but they had larger cities now.
Also, since the golden age just ended, and we don't have any cities except a few putting in infrastructure, we decide to mobilize for war. Unfortunately, this will need to last until we make peace with Korea (who will be the last opponent). Dang, I had hoped that mobilization would apply to ships. But it does not. Oh well. At least they still can get built when mobilized. Nor does it apply to cannons

.
And we gain control of Sun Tzu's Art of War and J. S. Bach's Cathedral:
Athens sits on a cow, but we'll keep it. I hadn't realized that the elimination of an AI would demobilize one's nation. We remobilize and go back to crushing resistance. The luxury slider goes to 0%, since we can use more money in purchasing armies, core cities still have "we love the Great Instigator" days in effect, and soon upgrading to artillery guns.
590 AD - Persia makes peace with Sumeria. Sumeria, Korea, and Persia have The Corporation. Of course, we pick it up and gift it to The Byzantines.