Tridam is a town in Poviss ruled by a baron and made famous by the Tridam ultimatum. The scenario entailed some brigands taking a boat full of innocent people and killing them one by one until the baron gave in to their demands. The baron was left in an unwinnable situation. He did capitulate and give in to the brigands saving further bloodshed, but many citizens blamed him for the deaths that did occur and postulated that storming the ship would have saved more lives.
Caldemeyn relates this story to Geralt over breakfast in the short story "The Lesser Evil".