The False Jenoine Invasion was a plot by the Jhereg to fool the Empress Zerika into using the Orb to locate Vlad Taltos. The Jhereg Council found a credible way to make the Empire believe that a Jenoine invasion was imminent, and the easiest way to stop it was to locate a certain Silver Tiassa, last seen in the hands of Vlad Taltos.
The Jhereg intended to use the discovery of his location and attempt to assassinate him, but were thwarted in their attempts by the intervention of Norathar, Cawti, and, to a much subtler effect, Daro.
Zerika was furious at the deception but eventually accepted that direct action against the Jhereg Council would damage the Empire far more than executing a scapegoat and letting the matter drop short of finding the ultimate planners.
This event is detailed in Tiassa.