As I was consolidating my gains, and putting the captured French slaves to work, Marseilles flipped back to the French. Sacre bleu! I guess I need more culture back home; only one wonder. I positioned forces to re-conquer, once the peace treaty expired. I was still able to negotiate deals with the Americans, Iroquois and Egyptians on the main continent and didn't want to trash my rep.
By 1380, I had planted a few towns between Paris and the flipped Marseilles, to provide a cultural buffer -- tiles which had my culture, worked by native citizens (not aliens), so that my conquered cities in the east and south would not share a border directly with the French. I garrisoned Paris and Lyons, and finished quelling the resistance.
Still a lot of turns before the treaty expires, so I revolted to switch to Monarchy. Lot of fighting still to come, so better to be prepared. N.B. I did revolt *after* the Golden Age ended, naturally. This also occurred when I was 2-3 turns away from finishing Military Tradition. I had built 47 riders before the revolution, and once I got MT, I would have to build Cavalry.
During this time, America and Egypt declared war on the Aztecs, the little brother civ on the main continent. I declined to be dragged into it, though Joanie joined in, crippled though she was. Maybe Abe pays well?
Chartres also flipped back to the French, but no matter. I was going to clean house in Marseilles anyway; what was one more city to cleanup?
Once in Monarchy, I also moved some of my ships to the western border waters, close to Marseilles. Once I had overrun it with riders, I would scoop them up and invade the large island just to the north. It is the stepping stone to the mainland.
The war was swift, and devastating for the French. By 1475, I had swept over the island and sliced through all but one town on the mainland. It took a while to get to Cherbourg, because Lincoln decided not to renew the ROP I had with him. So I had to go through the mtns and around him. Sometime during my war, I got the notice that Abe and Cleo had wiped out the Aztecs. Sorry, Monty.
So, by 1500 or so, I had wiped out the French, had begun building Cavalry, and moved a sizable contingent of riders onto the mainland. I began producing settlers, to settle some of the open land left by the Aztecs and to fill in the French land mass.
My plans (as of the 1510AD save), is to plant lots of towns in "Olde France". Yes, they will be mostly corrupt, but I can get a good deal of science out of them, using specialists.