Mobile Suit Gundam MSV-R Legend of the Universal Century Heroes: The Fabulous Shin Matsunaga - Vol. 2 Ch. 12 - Consideration

[MangaDex]

 

[justinbalisang2005]

So that gives us three Zeon Coup Attempts. The one that happened before the war (UC 0077 with Gadem), this early one (w/ Shin Matsunaga and Ramba Ral), and during the near end of the war (Plot to Assassinate Ghiren).