A Space Marine Force Commander who trained under Gabriel Angelos and now leads five Companies into battle using a tactic called 'Steel Rain' where entire Companies worth of Space Marines are held in reserve in Space and are deployed via Drop Pods on the battlefield. Because of this he doesn't concentrate too much on stationary defences such as turrets, preferring to keep the pressure up on his enemies until they break and flee.
Because of the Kaurava Conflict he was forced to fight against the fellow Imperial forces of the Sisters of Battle from the Sacred Rose and the 252nd Conservator Regiment of the Imperial Guard. When the Blood Ravens defeat the Sisters of Battle, they provided them with medical aid before shipping them off to the mercies of the Inquisition at the Convent Sanctorum on Ophelia VII, however because of the Imperial Guard's suspected involvement with Chaos at the start of the Conflict the Space Marines were given permission to fight against the Guard unlike they had on Kronus, and when they defeated the Guard they gave them medical aid just the same as they had done the Sisters of Battle before ferrying them off to Segmentum Command where the Inquisition "dealt" with them.
If Boreale succeeds in taking the rest of the Kaurava System, he trains Planetary Defence Forces capable of defending the Kaurava System. He also has accusations of heresy silenced because of the Blood Ravens' actions on Kronus, redeeming their honour and are granted a Fortress-Monastery on Kaurava II and in honour of Force Commander Boreale the province was renamed Borealum.
Following 'Soulstorm', Commander Boreale continues to be referenced in the series. In 'Dawn of War II', a conversation between Scout-Sergeant Cyrus and Sergeant Thaddeus confirms that - canonically - Boreale's campaign in the Kaurava system was a devastating failure. In fact, losses incurred by the Blood Ravens were so great that - had the Blood Ravens failed to protect their recruiting worlds from the Tyranid onslaught in 'Dawn of War II' - they would've been finished as a Chapter.