In October 1913 PD, MacArthur was assigned to a reinforcement squadron commanded by the senior StateSec officer in the Shilo Sector, Major General Prestwick Thornegrave, which had been sent to the Seabring System, recently recaptured by the People's Republic of Haven in the aftermath of Operation Icarus.
As with all other units of General Thornegrave's squadron, MacArthur was ordered to surrender by Admiral Honor Harrington, who had led an uprising among the inmate population of Hades which had succeeded in defeating the planet's State Security garrison. MacArthur surrendered with the rest of the StateSec squadron, as there was no chance for the Havenites to either evade or defeat Hades' planetary defenses.
As Commodore Ramirez's falgship MacArthur participated in the Battle of Cerberus and contributed to the utter annihilation of General Seth Chernock's task force. After the battle, MacArthur and the rest of the Elysian Space Navy embarked as many former inmates as she could and left the Cerberus System to join the Allied forces in Trevor's Star.
- Commander Solomon Marchant – Commanding Officer (Prize Master)