Imperator IV-class Star Destroyer

Development for the Imperator IV-class Star Destroyer started in 29 ABY with a fully functional prototype built by 31 ABY. Like most First Order capital ships, the Imperator IV-class featured very thick armor, strong shielding and powerful main weapons, though unlike most other First Order capital ships the Imperator IV-class did not sacrifice mobility. This was a clear disregard of the New Republic's demands that the First Order's military was solely for defense with the First Order following this by developing their capital ships to be heavily armed, heavily armor, but slow capital ships that would park in a defensive position in a planet's orbit and stay here relaying on the ship's advanced gyroscope to keep the front of the ship pointed at enemy vessels.

Knowing the New Republic would never allow the construction of the Imperator IV-class, the ship was developed, tested and constructed in a remote research and construction facility located in a nebula, safe from New Republic scanners. For three years the ship was constructed in secrecy with the idea being that once they had enough of them, they'd reveal them to the Galaxy now having the military strength to rival the New Republic. These ships would become the First Order's new main capital ships, keeping their trade routes open and safe and guarding their borders against any would be invaders. However, in 34 ABY the Resistance revealed it'd true strength by destroying the solar system the New Republic's capital was located in with their Super Weapon called "Starkiller Base".

Even though the First Order didn't have the number of Imperator IV's that they wanted, the 150 they managed to build were rushed to vital area of the First Order expecting at any moment a Resistance invasion.