High Quality Content by WIKIPEDIA articles! This is a list of events held and scheduled by Strikeforce, a mixed martial arts organization based in the United States. The first event, Strikeforce: Shamrock vs. Gracie, took place on March 10, 2006. As of Strikeforce Challengers: Britt vs. Sayers, which occurred November 18, 2011, there have been 56 Strikeforce events held. Upcoming events are listed in italics.