The Inner Colony Wars were a series of conflicts that occurred sometime in human history. Very little is known about the wars, or if they were a distinct event at all. Of what is known, "instant, uninformative news reports caused massive civil unrest" and "almost tore down Earth's culture." 
WARNING: The following information is conjecture and not official information.
Assuming that the Inner Colony Wars were a distinct event and that the name "Inner Colony Wars" has been in use since the war itself, they may have occurred in the 25th century as there obviously was no distinction between Inner and Outer colonies before the establishment of the Outer Colonies.