I would continue to build longbows in preparation to eliminate Alexander entirely, but first I need a pause to recover from all the brutal whipping.
I have a score lead, but it's a bit of an illusion; that's mostly from my capital's ring-4 cultural expansion and mostly doesn't reflect workable land. 40 GNP is also illusory; 24 of that is just culture from Stonehenge and its monuments.
The demographics tell a chilling story: I have HALF the population of my WORST rival. But the real telltale here is Food Production, where I'm above average and right with the pack. I'll be able to regrow quickly, especially with our cheap granaries finally online.
And to catch me right back up in the tech game, Boudica my beauty came up with this beauty!
Silly AI - when you're the only one with Alphabet, the worst thing you can do is give it away and let your rivals start trading without you. My own next research was clearly Construction, for the nice resourceless catapults, and also our UB.
I had previously resolved not to sign any Open Borders agreements, but I did so for the moment with Alexander. His contact links will disappear when I kill him, and in the meantime I can scout out his land for conquest plans and pick up a few pennies of trade route income. Sun Tzu would approve.
Speaking of contacts, here's how they've worked out.
Every rival has contacted its neighbors; that was expected and unavoidable. But there's one unapproved relationship on that list. During our war, Louis had slipped a scout through my land all the way over to Monty's slice. I did manage to kill it before it also contacted Mansa.
Some historian wrote me a Most Powerful chart, which also helps for war planning. Look who's at the bottom, my target Alexander. And look who's not on it at all, Isabella. Keep that in mind. Boudica and Caesar are the scary ones; I'm keeping the cities in their directions well-defended with two CG3 longbows and walls.
HOLY CRAP THAT'S AWESOME! My best commerce city just popped GOLD! I never get a "meh" resource pop. Every pop I get is killer awesome.
Boudica founded Christianity, and I realized I had a problem. I had no religions yet anywhere, which struck me as odd... then I realized I had not opened borders for any to spread. Alexander, my conquest target, didn't have any either. I might have to go the entire game without faith, until I conquer some?
Back to war planning, I'm gearing up to go after Alexander again. To secure an economic edge, I really need to claim a slice of pizza for myself. A civ's economic strength is determined not so much by the number of cities it has, but the number of back-line cities. Sheltered provinces can pour all their effort into economy; they can build all the cottages and libraries they want without any worries of protection or pillaging. Front-line cities always have to be prepared to defend both themselves and their surrounding countryside.
My remaining units from the first war were fairly few: only three longbows, and three holkans including the GG. I reinforced the army with three more each swords, longbows, and catapults.
Anyway, I declared war again... the big question would be whether Alex could buy any help with his Mathematics and Construction. I considered gifting them all round to prevent that but decided not to.
Between turns -- oh no! The war horns sounded again!
But it was Isabella declaring on Sitting Bull...?!?!?! Without Open Borders with me, they can't even reach each other, so I don't know what they're trying to do.
Of course, no war report is complete without some amusingly deficient AI tactics. My stack of doom was lined up on a hill, ready for a long bloody assault on St. Petersburg. So of course, the three catapults in the city naturally thought it would be a better idea to abandon the battle altogether and try to reach lightly-defended Novgorod instead. And my veteran longbows naturally dismantled those catapults without blinking.
I captured the two Russian cities. As I then advanced on Moscow, Alexander came up with Metal Casting, but refused to cough it up for peace. I was racing to grab Moscow before he traded it, and won that race.
One pizza slice down, seven to go. Although my Medic III General died trying to knock off the last unit in Moscow at 97% odds. 
Yes, that's +14 gold at 0% research - my entire net GNP is +14. But I'm keeping up thanks to conquest cash and monopolizing brokerages. I researched Currency with my conquest cash, traded that to Caesar for HBR and brokered that to Mansa for Code of Laws.
Yes, it's 715 AD and nobody has Metal Casting. Tech is going crazy slow - which is just fine for me, more time for my longbow slingshot to rule the world.
And yes, Louis just declared war again. But I was thoroughly ready this time - my elite Russian units were just getting back home.