This quest begins immediately after War Efforts. Now that you’ve won the favour of numerous Irish kings by helping them with Royal Demands, it’s time to report to King Flann at Knockfree, located in the northwest of Meath.
This is a simple quest which only requires that you speak with King Flann, who can be found near the centre of the settlement. Once you do a brief cutscene will play out, after which your alliance with the Southern Army will be confirmed. The quest will end sooner after.