In the year 2267, he took the Constellation to meet with the ISS Enterprise, to sort out the issue of command of the latter starship following its mission to Halka. However, by the time the rendezvous took place, the issue had already been resolved with the death of James T. Kirk and Decker merely confirmed Spock as the new captain. (TOS comic: "Fragile Glass")
In 2277, under orders from Empress Hoshi Sato III, Decker led a fleet to the Terra Nova system in the hopes of ambushing and destroying the ISS Enterprise. When the Enterprise arrived in the system, Admiral Spock quickly surrendered and had himself beamed aboard the Constellation to hear the charges laid against him by Decker.
Unfortunately, Spock had managed to persuade the Constellation's first officer, Commander Hiromi Takeshewada, to lead a mutiny. Takeshewada assumed command of the Constellation after shooting Decker in revenge for all the taunts that he had made against her. Spock succeeded Decker as Grand Admiral. (TOS - Mirror Universe novel: The Sorrows of Empire)
|Grand Admirals of the Imperial Starfleet|
|Garth of Izar • Matthew Decker • Spock • Zhao Sheng|
|Emperor John Gill's cabinet|
|Melakon (security minister) • Rota Sevrin (science minister) • Tristan Adams (propaganda minister) • Raymond Stiles (genetic purity minister) • Harcourt Mudd (revenue minister) • Samuel Cogley (minister of vassal affairs) • Matthew Decker (war minister)|