The Mackensen was to be the lead ship of seven (later reduced to four) battlecruisers built for the Imperial German Navy. The class was originally designed in 1912 as a successor to the Derfflinger-class battlecruiser, essentially being upsized and armed with heavier 350 mm guns. However, after the Battle of Jutland, the last three ships of the class were redesigned into the Ersatz Yorck class, to be armed with 380 mm guns.

Although the Mackensen was expected to be constructed in 1914, the outbreak of the Great War postponed the construction of the entire class. It was not until 30 January 1915 that the ship was laid down at the Blohm & Voss shipyard in Hamburg, and 21 April 1917 until it was launched. However, due to resource shortages, Mackensen along with her sister ships were never finished. Due to her advanced stage of construction, the British initially believed that she was completed and listed her as one of the ships to be interned at Scapa Flow in 1919. After the war, the hull of the Mackensen was stricken on 17 November 1919 per the Treaty of Versailles, and was later scrapped in 1922 at Kiel.

The Mackensen was introduced during Update "Leviathans" as a reward for the 2025 "Black Hussar" event. The Mackensen is largely similar to her half-sister Ersatz Yorck, with the smaller but faster-firing 350 mm guns being the main difference. The guns have two shell options: a SAP shell with poor penetration that is barely useful against capital ships, and an AP shell with below average penetration but a high amount of filler. Much like the Ersatz Yorck, the Mackensen is relatively survivable, though retains the weakness against aerial attacks and plunging shells. The latter is further exacerbated by the placement of the secondary magazines above the waterline, which may cause a chain detonation when hit.