Canon Background
https://awoiaf.westeros.org/index.php/Jon_Connington

In-Campaign
In his newly appointed role as Hand Of The King forces led by Jon tracked Robert Baratheon to Stoney Sept. There he coordinated a search and imprisoned the town’s steward, Shaymus. He was forced to retreat when Lords Stark and Tully arrived with their great host. He was later stripped of his titles and sent into exile in Essos.