Okay I'm willing to surrender, a quick summary of this front:
Suboptimal has stalled out in his advance here on my army of field cannon corps. We've traded some units and it seemed like we were holding here, but then I see this disaster (which only took a few ingame turns) on rho's side:
He'll soon lose all his coastal cities, and then it's time for mine. All I have to put up against battleships are field cannond and medieval walls. And that's not the worst part, the worst part is that he has Steel so his cities get the instant-cheat-walls as well at better fortification than my walls could ever be. Even if rho and I somehow push back on land, he can just city and ship bombard us to death from the comfort our own coastal cities.
GG Suboptimal
(I mean unless rho wants to continue this fish in a barrel shoot, but I haven't seen him make any big moves for the past 30 turns)