Sweden never signed the peace treaty with San Marino in the Westphalian Peace in 1648. According to Swedish officials and diplomats that doesn't mean anything since Sweden and San Marino never were in war de facto.
Unlike this, the town of Berwick-upon-Tweed, which has a kind of autonomy within the UK, signed a separate peace treaty with Russia in 1966, which ended the Crimean War. The British ambassador at the time said to his Russian counterparts that "Now you can tell the Russian people that they can finally sleep peacefully in their beds".