The Mattingly evacuated the Deltan Prime Minister off Delta IV when it was invaded by the Borg and the Cybermen on stardate 45635.2, in the year 2368. (TNG - Assimilation² comic: "Issue 1") The work of the Enterprise crew and The Doctor and his traveling companions led to the prevention of the Borg/Cyberman alliance, so the events at Delta IV were erased from history beyond the people involved having maintained their memories. TNG - Assimilation² comics: "Assimilation², Issue 6", "Assimilation², Issue 8"