A year during the Armageddon War.
The first MDS to be cornered on the execution order is MDS Lucius on Galvian VI. This ends with the destruction of the 97th, 506th, 24th, and 232nd Omega Marine Battleforces. They were slaughtered down to the last man. Lucious killed them all while the 5th Omega Fleet sat in orbit. At this point, the fleet commander, General Hansura, ordered the extermination of the planet. Orbital bombardments destroyed the entire surface. After the hours of bombardment were done, Lucius was found to have survived. There was no possible way off the planet, therefore the choice was made to leave him there. An unknown time after this, Lucifer confronted Lucius and offered him immortality and rose him to demonhood, becomming the first fiendish MDS.