During the UN-MCR Cold War Captain Yao commanded the Flagship MCRN Donnager along with several internally docked Morrigan-class Patrol destroyers in Operation Silent Wall to destroy the Pirate threat to Martian shipping lanes.
Donnager would later deploy to Phoebe where its Martian research team was found to have been killed mysteriously. The Donnager then transferred back to Mars where it received a distress call from the shuttle Knight. The survivors were rescued when the Martin battleship was attacked and boarded by unknown ships. Captain Yao ordered Condition Zero and after the civilian survivors escaped onboard the MCRN Tachi the ship was scuttled, completely destroying it.
At the jointly operated UN-MCR station on Ganymede several UN Marines were attacked by a Protomolecule Hybrid. The UN Marines retreated towards nearby Martian Marines who engaged the Hybrid unsuccessfully. Communications were being jammed and this led to confusion in orbit with both the UNN and MCRN fleets believing their own forces were under attack by the other. Both fleets engaged causing significant damage to the mirrors in orbit.