The 689th Cadian Steelwall, led by Colonel Marcus Valerius, arrives on Duros IV as the last regiment to reinforce the Imperial forces. Known for their mechanized infantry and urban warfare expertise, they are immediately deployed to the front lines to bolster the defenses at Fortress and other critical positions. The arrival of the 689th brings renewed hope to the beleaguered Imperial defenders, as they bring with them fresh troops and the ability to quickly respond to the shifting tides of battle.