Years prior to 3 ABY, in the midst of its war against the Rebel Alliance, the Galactic Empire located a base belonging to the rebels on the Outer Rim planetoid Polis Massa and proceeded to bombard it. The attack caused damage to a Chroon-Tan B-Machine midwife droid.
ZED-6-7, an Imperial forensics droid, remembered the bombardment in 3 ABY. This occurred when he accompanied Darth Vader, the Dark Lord of the Sith, to Polis Massa—Vader was seeking retribution on those who had concealed his son from him—and they discovered the remnants of the base. The droid also reported that he found no signs of any living organisms.
The comic series Star Wars: Darth Vader (2020) first referenced the Polis Massa bombardment in its fifth issue. Marvel Comics released the issue, penned by Greg Pak, on September 16, 2020.