The First Sith Imperial Strikeforce was a unit within the Imperial Navy formed both by members of the One Sith and Navy officers, particularly Skull Squadron. It was commanded by Grand Admiral Rulf Yage and his fellow Moff, the Chiss Fehlaaur'aitel'loro. In 137 ABY the strikeforce was sent by Regent Morlish Veed to complete Operation: Thunderstroke, a mission to capture Emperor-in-exile Roan Fel at Agamar. The topmost Sith within the strikeforce was Darth Rauder, whom oversaw all pilots, both Sith and non-Sith.
During the ensuing battle, the strikeforce's flagship, War Hammer, destroyed the Fel-loyalist Star Destroyer Dauntless, under the command of Admiral Tohri Challon, but failed to stop Roan Fel from escaping in his shuttle.