This game recently ended. It's a modern diplomacy game in which I was Germany. In the opening year's moves, I grabbed Sweden. Russia also tried to move there. I hadn't talked to Russia prior to that (which I should have), but did contact him after with an offer of peace. He demanded Sweden, which I refused to give him. I offered my help elsewhere, but he was insistent. In the end, he attacked Sweden and we were at war. It didn't end well for me, obviously, as I thought Poland was my ally and he sided with Russia, and my other two allies--England and Italy--were overrun relatively quickly.
As confrontational as Russia was being in this case, I doubt I would have avoided war even if I had given up Sweden. My question, though, is this: is it ever better to cede a supply center, especially a neutral center you haven't really taken from any other player, to keep the peace, or does this only stave off defeat for a time?