10 Star Trek Assassinations That Changed Everything
5. Former Obsidian Order Officers
With the final stages of the joint Obsidian Order/Tal Shiar operation in the Gamma Quadrant, Enabran Tain saw fit to start cleaning house. We as an audience first became aware of this when Garak's Tailor's Shop exploded on the promenade, even if that had been caused by the former agent himself.
The assassinations of the former operatives served to draw Odo, already investigating events thanks to Garak's actions, further into the situation - something that ended up saving Garak's life, the life of the crew of the Defiant, and forwarning the Alpha and Beta Quadrants to the eventual assault by the Dominion.
Colonel Lovok had been the Romulan Commander of the operation and had, at an earlier point, been replaced by a Changeling. This Changeling, citing the golden rule that 'No Changeling has ever harmed another' helps Odo and Garak escape the battle, which in turn is almost certainly responsible for the successful escape of the Defiant.
It would take the deaths of the last operatives of the Order to truly shock the rest of the Galaxy into preparing for the Dominion Invasion. In a way, Tain did set the wheels in motion to save his homeland - it just took several wildly roundabout routes to get there.