Horus' advance on Terra reached the Ollanz Cluster at this time, encountering Loyalist reinforcements bound for Beta-Garmon rearming and refuelling at the Borman System. The Loyalist fleet rapidly redeployed to oppose the Traitors' advance and to protect the valuable, resource-rich worlds of the star cluster.
The turning point of the brief but intense conflict came at Borman IV, when a demi-legion of the Legio Astorum, who were also known as the "Warp Runners," launched a daring offensive towards the world's beleaguered capital city.
The crucial Titan battle took place in the volcanic Yrevendi Desert immediately to the north of the capital, as Princeps Seniores Varr Harax led a surprise thrust through rough terrain at a weak point in the Traitor Legio Fureans lines, accompanied by ground forces drawn from the Iron Hands Legion.
The "Tiger Eyes", as the Legio Fureans was also known, had been drawn away by a bold diversionary attack and were annihilated by the Warp Runners, who were able to break through the Traitor Emperor's Children Legion lines and reinforce the beleaguered capital city.
Ultimately Borman IV and the entire Ollanz Cluster were delivered from the Traitors' possession, allowing for Loyalist forces to be redeployed to their original destination at Beta-Garmon in time for the final battle that Horus would face on the road to Terra.
- Adeptus Titanicus - The Horus Heresy: Rulebook (Specialty Game), pg. 17