Third Frontier War
(979 to 986) marked the end of an uneasy peace that lasted nearly 350 years. In that time, the Zhodani territory in the Spinward Marches expanded to include four new systems (extending down into Querion Subsector from Cronor). The Imperium retained Retinae as an Imperial territory and expanded its holdings in the Five Sisters Subsector. In 979, Zhodani battle fleets struck at Jewell and Querion after several years of sabre-rattling. The Imperial reaction was deficient initially, although reinforcements were soon brought into the battle. The Third Frontier War was less characterized by the planetary sieges of previous wars, and more by commerce raiding, deep thrusts by cruiser squadrons to disrupt shipping, and by harassment of civilian shipping.
The damage done to the civil populace, and the lack of progress in the war turned public sentiment against the high command, and ultimately against the Emperor, who it was felt was prosecuting the war too slowly. Ultimately, an armistice was reached which ceded systems to the Zhodani in the Jewell Subsector and allowed Zhodani occupation of several in the Querion Subsector. Moreover, the Imperium withdrew several parsecs from their previous positions, creating a demilitarized region through much of Vilis Subsector. With the Zhodani on their doorstep, Retinae applied for, and was granted, disunion from the Imperium. The outcry against the peace settlement when it was announced was enough to force the abdication of the Emperor Styryx. Nevertheless, the settlement created reasonably secure borders along the Zhodani frontier, and allowed the Marches to continue with their commerce and industry.