The save at 450AD
Pre-turn (350AD): Stared at this one for a while. First, we dont need courthouses in the core. Viagra Falls courthouse (3) > harbor (1). Same thing for Mauch Chunk, courthouse (6) > harbor (1). Little Big Horn market (19) aqueduct (7). Rheims courthouse>treb. Peace and 99 gold to France for engineering, feudalism, monotheism. Chivalry in 7. Move troops out of Grenoble and abandon it. Start destroying roads between Dijons and Tours in case the Japanese try and come through from that direction. Start tearing up roads around Besancon, which includes the dyes. Shenandoah to Latrobe and builds army. Salamanca MW>MI.
IBT- Lose 2 MWs to Japan at Besancon. Viagra harbor>MI. Cattaraugus courthouse>MI. Oil Springs market>MI. Mauch Chunk harbor>pike. Mystic temple>settler. Spanish building Bachs.
Turn 1 (360AD). Tear up all improvements except 1 tile with road/mine at Besancon. Give Besancon back to France so Japan doesnt capture it. Sell off the Drake and a warrior to cut unit costs.
IBT- Japan advances one samurai south of Besancon. Dont see any others.
Turn 2 (370AD). Contact Dad. Hes willing to listen to his wayward sons appeal for life. Peace Treaty straight up?

Absolutely, and thank you sooo much. Next time you need gems, just say so, and Ill ask what carat. Hurry worker in Tours for 20g. Tona needs a taxman.
IBT- Paris worker>temple. Tona market>temple.
Turn 3 (380BC) Hurry worker in Avignon for 12g. Found Kente. Have to crank lux up a notch to keep people happy.
IBT- Centralia market>harbor.
Turn 4 (390AD) worker actions essentially
IBT- Not much. Some builds come in.
Turn 5 (400AD) More worker actions, getting settler north.
IBT- Nothing much.
Turn 6 (410AD) More worker actions. All the captured French towns like Lyons are now starved down.
IBT- Fatherland is trying to get a settler pair snuck in. Rheims settler>rax. Little Big Horn starts temple. Chivalry in, start invention with a scientist, sci to zero.
Turn 7 (420AD) Our settler 4 turns from getting into the spot Daddy T is trying to get to. Mauch Chunk needs a taxman to keep happy. Sneak a peek at Besancon with an MW, its deserted!
IBT- Aztecs finish Bachs. 2 French workers appear by Besancon.
Turn 8 (430BC) Worker actions.
IBT- Not much, samurai settler pair move off. Aztec pike and MI in their area by Tula.
Turn 9 (440AD) Change Cattaraugus from market to FP. We need a good second location, and it looks to be as good as any we can reasonably expect. Due in 22.
IBT- Sala knight>knight
Turn 10 (450AD) 96 gold spent for embassy in Kyoto. Building university, with about 6 musketman guarding. And its right off the Byzantine border. Get the feeling Constantinople is just in the fog to the west of it. Otherwise the cultural border would be a lot farther out in that direction. Of course may just be a core Byzantine city. Dads ire now downgraded from furious to annoyed. Settler is now 2 west of Tours so can settle in the area next turn or two. Army is in Latrobe waiting to be filled by MI or knights. Back to diplomacy, gems, silks 134g and territory map to Japan for invention. Gunpowder in 50. And done.
The scorched earth exercise at the start can be second guessed all day long, but in the end, what we needed most IMHO was time in order to get chivalry and have some MA units to counter the Samurai in whatever quantity they finally came. At the cost of Besancon, Grenoble and 2 MWs we got peace, and that was a lot sooner than I expected. Tearing up the roads was just to buy enough time to get Dad to the peace conference, and the fact we did not kill any of his units, and settled things in 10 turns was very lucky. Now we have peace with Joan for 10 more turns, and we can get back to Besancon if we so choose. And the settler by Tours can re-settle old Grenoble. Our cash flow is 60gpt, so that should be worth something before too long. If nothing else, the gem and silk deal will keep Japan off our back while we tend to more important matters.
We could use a rax somewhere up north, to heal and upgrade units. Rush prices are running around 120+g near the ex-French towns. The Mongol settler pair was surrounded by Tours and can be released if desired.