After the outbreak of World War II in September 1939, they were used in a variety of roles, including as minelayers and escort vessels.

Leipzig provided some gunfire support to German Army troops fighting on the Eastern Front.

[2] The ships' hulls were divided into fourteen watertight compartments and had double bottoms that ran for 83 percent of the length of their keels.

[2] Both ships carried one aircraft catapult for a pair of Heinkel He 60 biplane reconnaissance float planes.

[4] The ships' propulsion system consisted of two steam turbines manufactured by the Deutsche Werke and Germaniawerft shipyards, along with four 7-cylinder double-acting two-stroke diesel engines built by MAN.

[1] Steam for the turbines was provided by six Marine-type double-ended, oil-fired, water-tube boilers, which were vented through a single large funnel located amidships.

With only the turbines in operation, the ships could steam for 2,800 nmi (5,200 km; 3,200 mi) at a speed of 16.5 kn (30.6 km/h; 19.0 mph).

[2] Steering was controlled by a single balanced rudder, which gave the ships excellent maneuverability.

Both vessels also suffered from severe leeway at low speeds, and the effect was especially pronounced for Nürnberg, owing to her larger superstructure.

The belt was inclined to a greater degree than in the preceding Königsbergs, to increase the effectiveness of the same thickness of armor plate.

[11] Leipzig had her anti-aircraft armament modernized to bring her closer to the standard of weaponry fitted to her sister.

In late 1942, a pair of Army-variant 2 cm Flakvierling quadruple mounts were installed, one on the navigating bridge and the other on top of the aft superfiring turret.

Two Navy-pattern Flakvierlings were added; one replaced the Army model atop the aft superfiring turret, and the other was placed in front of the anti-aircraft fire director.

In late 1939, after the start of World War II, she performed escort duties for warships in the Baltic and North seas.

She provided gunfire support to the advancing Wehrmacht troops as they invaded the Soviet Union in 1941.

Instead, they repaired Leipzig enough to keep her afloat, and in that state, provided gunfire support to the defenders of Gotenhafen against the advancing Red Army in March 1945.

After the end of the war, Leipzig was used as a barracks ship for minesweeping forces and was scuttled in July 1946.

After the outbreak of World War II in September 1939, she was used to lay defensive minefields off the German coast in the North Sea.

[17] She was thereafter used to escort offensive mine-layers in the North Sea until she was torpedoed by the British submarine Salmon on 13 December 1939 in the same attack that hit her sister.

[18] After repairs were completed in early 1940, Nürnberg returned to active duty as a training ship in the Baltic Sea.

In January 1945, she was assigned to mine-laying duties in the Skaggerak, but severe shortages of fuel permitted only one such operation.