SMS Frankfurt was a light cruiser of the Wiesbaden class built by the German Kaiserliche Marine (Imperial Navy).

This freed the design staff to adopt the new 15 cm (5.9 in) gun for the new ship's main battery, which the German fleet had sought for some time.

The decision to move to the larger gun was in large part driven by reports that the latest British cruiser, HMS Chatham, would carry a complete waterline armor belt.

[6] The winter months passed uneventfully, and in March 1916, Frankfurt began the normal wartime operations for II Scouting Group: patrols in the southern North Sea to defend the German coast and sweeps for British warships.

Boedicker initially ordered his battlecruisers to continue with the bombardment, while Frankfurt and the other five light cruisers concentrated to engage the Harwich Force.

[8] On 24 May, Boedicker temporarily transferred his flag to Frankfurt, and he remained aboard during the fleet operation that began on 31 May and resulted in the Battle of Jutland.

Frankfurt steamed in the leading position of the wedge-shaped formation at the head of the German line of battle at the start of the action.

Frankfurt was engaged in the first action of the battle, when the cruiser screens of the German and British battlecruiser squadrons encountered each other.

Half an hour later, the fast battleships of the 5th Battle Squadron had reached the scene and opened fire on Frankfurt and the other German cruisers, though the ships quickly fled under a smokescreen and were not hit.

[10] At around 18:30, Frankfurt and the rest of II Scouting Group encountered the cruiser HMS Chester; they opened fire and scored several hits on the ship.

Almost two hours later, Frankfurt encountered a pair of British destroyers and fired on them briefly until they retreated at full speed.

Two days later, Frankfurt was docked in Kiel for a planned shipyard period that included modifications to her main battery and the installation of a larger charthouse suitable for an admiral's staff.

[6] The raid resulted in the action of 19 August 1916, an inconclusive clash that left several ships on both sides damaged or sunk by submarines, but no direct fleet encounter.

[16] Frankfurt next sortied on 23 September, leading II and V Torpedo-boat Flotillas on a sweep to the south of the Dogger Bank that concluded the following day without having located any British warships.

The failure of the operation (coupled with the action of 19 August) convinced the German naval command to abandon its aggressive fleet strategy.

[6] The ship's activities through the first half of 1917 were largely restricted to local defensive patrols in the German Bight, and she saw no action during this period.

[24] The following month, Frankfurt joined a major sweep outside of the German Bight led by the dreadnought König Albert from 2 to 3 November.

[24] Along with three other cruisers from II Scouting Group, Frankfurt escorted minesweepers clearing paths in minefields laid by the British.

[24][28] On 21 January 1918, Frankfurt and the rest of II Scouting Group returned to the Baltic for another training period that lasted until 10 February.

On 10 March, Frankfurt sortied in company with the cruisers Emden, Graudenz, and Bremse and three torpedo-boat flotillas for a sweep through the Skagerrak and Kattegat to search for British merchant shipping to Scandinavia.

The former was transferred back to the North Sea, where she relieved Graudenz as the flagship of the fleet's deputy commander of torpedo-boat flotillas.

[30] While on patrol duty in the German Bight on 30 September, Frankfurt damaged one of her propellers, which required repairs at the Kaiserliche Werft in Wilhelmshaven that began that day and lasted until 8 October.

[31] In the final weeks of the war, Scheer and Hipper intended to inflict as much damage as possible on the British navy, in order to secure a better bargaining position for Germany, whatever the cost to the fleet.

[31][37] The German ships were escorted by the Grand Fleet and vessels from the other Allied countries to internment at the British naval base in Scapa Flow.

Reuter believed that the British intended to seize the German ships on 21 June 1919, which was the deadline for Germany to have signed the peace treaty.

On the morning of 21 June, the British fleet left Scapa Flow to conduct training maneuvers, and at 11:20 Reuter transmitted the order to scuttle his ships.

[40] She was raised on 12 July, and remained in Scapa Flow while negotiations as to her final disposition (and those of other surviving German warships) were settled.

On 17 January 1920, the Allied powers agreed on a final list of war prizes, and Frankfurt was allocated to the United States as a propaganda and testing ship.

The three minesweepers then towed three ex-German torpedo boats in company with Ostfriesland and Frankfurt; the convoy then crossed the Atlantic to the New York Navy Yard.

[44][45] In July 1921, the Army Air Service and the US Navy conducted a series of bombing tests off Cape Henry, Virginia, led by General Billy Mitchell.