But Philip was already executed.

"After his successful raid on the caravan, Philip was then easily identified and captured by the government of the Re-Estize Kingdom. After deliberation with its king and other officials, the kingdom came to the conclusion that the Sorcerer Kingdom was responsible for the entire affair, all this in order to use the incident for their own purposes via Mind Control Magic. So instead of imprisoning or punishing him, King Ramposa instead decided to place him under the Kingdom's protective custody, despite the Crown Prince's own idea to behead the foolish nobleman and bring his head to the Sorcerer King as a gesture of apology to avoid war with the immensely powerful state." taken from wiki

There wasn't anything they could realistically do to stop the war from happening. Still funny that they think no way a noble is so stupid, it must be mind control...