The Siege of D’Qar took place in 34 ABY in the days that followed the Battle of Starkiller Base during their war with the First Order.
Shortly after Starkiller Base was destroyed, the Resistance began evacuating their base on D’Qar. In orbit around the planet, General Organa commanded the Resistance fleet from the cruiser Raddus. The escape was interrupted by the arrival of a First Order fleet consisting of three Resurgent-class star destroyers and one Mandator IV-class Siege Dreadnought, the Fulminatrix. The dreadnought opened fire on the Resistance base almost immediately, but the base had been fully evacuated just in time. To buy time for the Resistance transports to escape, Commander Poe Dameron attacked the dreadnought in his X-Wing, eliminating its surface cannons and clearing the way for a squadron of Resistance bombers to attack despite counterattacks from the dreadnought and its TIE squadrons.
“…the Resistance must be destroyed before they get to Skywalker.”
“We have their location. We tracked their reconnaissance ship to the Ileenium system.”
“Good. Then we will crush them once and for all. Prepare the weapon.”
―Supreme Leader Snoke and General Armitage Hux