While initially disheartened by Chief Boden’s sudden exit from Chicago Fire, the TV show’s replacement for Eamonn Walker’s character has lightened my spirits, making me much more excited about season 13. The NBC procedural drama series, created by Michael Brandt and Derek Haas, debuted in 2012 and was an immediate victory for the network. Chicago Fire ultimately spawned a One Chicago franchise consisting of four shows, most of which have obtained similar success. Part of the reason why Chicago Fire has been so triumphant is because of its cast, and one of the original members was Walker as Chief Boden.
https://screenrant.com/chicago-fire-season-13-boden-replacement-dermot-mulroney-exciting/