The Resistance was a precautionary movement founded by Senator Leia Organa in response to the rise of the First Order; a military dictatorship that rose from the fallen Old Empire in the galaxy's unexplored space (the Unknown Regions) by staunchly loyal former Imperial hardliners.

As depicted in the events of Star Wars: The Force Awakens (2015), the First Order used the Starkiller Base superweapon to shatter the New Republic government and starfleet, leaving the galaxy vulnerable for conquest.

Eventually, the First Order, a remnant of Palpatine's regime, rose to power in the Unknown Regions and repeatedly ignored and violated the Galactic Concordance, rebuilding former Imperial fleets and mobilizing a new generation of stormtrooper forces in its expanding armies.

Kylo Ren attacks Takodana and takes Rey captive after learning she has seen the map, withdrawing the stormtrooper forces when the surviving Poe Dameron comes to aid with Resistance starfighter pilots.

The Resistance party then travels to the base's thermal oscillator to plant bombs and destroy it, leaving the weapon itself vulnerable, though, in the process, Han Solo reunites with his son.

Rey, Finn, and Chewbacca watch on as Han Solo implores Ben to return to his family and abandon the dark side, but Kylo Ren kills his father per the urging of Supreme Leader Snoke, hoping it will give him power.

With very little fuel and combat resources available, Holdo deduces that the only option for the Resistance is to evacuate to another planet via escape pods, a course of action that Dameron objects to, but is unable to prevent.

Meanwhile, Finn, BB-8, and Resistance technician Rose Tico embark on a secret mission to the planet Cantonica to find a slicer who can disable the Supremacy's hyperspace tracker, which turns out to be a man named DJ.

Finn and Rose are then taken to a hangar where they await execution, but before they can be struck down, Holdo turns the Raddus around and stages a suicide attack by aiming a hyperspace jump right through the Supremacy, tearing it asunder.

Finn, Rose, and BB-8 then fight their way out of the damaged Mega-Destroyer as it falls apart, defeating Captain Phasma in the process, and join the other surviving Resistance personnel as they gather on the planet Crait, taking refuge in an abandoned Rebel Alliance base.

The First Order, led by Kylo Ren, arrives on Crait and assaults the base, using a superlaser siege cannon, AT-M6 and AT-AT walkers to break down its heavy-duty doors.

Finn, Poe, R2-D2, and Chewie were first seen collecting Intel about Palpatine's return from the First Order's spy and fled back to their base using the Falcon after wiping off the TIE fighters that chased them.

The Resistance under command by Poe Dameron and Finn, traveled to Exegol with their fleet to face the Sith Eternal forces, including the Final Order, and ultimately emerged victorious.