Laid down at the AG Vulcan shipyard in Stettin in 1883, the ship was launched in December 1884 and commissioned into the Navy in April 1886.

Following the Franco-Prussian War of 1870–1871, General Albrecht von Stosch became the Chief of the Imperial Admiralty; he immediately set about drafting a new fleet plan that was based on the previous program that had been approved in 1867.

Stosch's fleet plan, finalized in 1873, called for a total of eight ocean-going ironclads and six smaller, armored corvettes suited for operations in coastal waters.

The last corvette was originally intended to be a fifth Sachsen-type vessel, but dissatisfaction with the design led many senior officers to push for a revised version.

[1][2][3] Work on the new design began in 1879,[4] but parliamentary objections to naval expenditures, particularly after the accidental sinking of the ironclad Grosser Kurfürst in 1878, delayed construction of the vessel.

Stosch initially sought to secure funding for two ships of the design, with the intention to retain one as a material reserve to be mobilized in the event of war, but the Reichstag refused.

Finally on 7 December 1881, the parliament voted to approve funds for Oldenburg, albeit an amount significantly less than the navy desired.

On speed trials, her engines slightly exceeded the designed horsepower, at 3,942 PS (3,888 ihp), though Oldenburg made only 13.8 knots (25.6 km/h; 15.9 mph).

After the end of the exercises in September, Oldenburg was assigned as the guard ship for Kiel, where she also conducted further sea trials under the command of Korvettenkapitän (KK——Corvette Captain) Max Plüddemann.

In June, Germany began work on the Kaiser Wilhelm Canal; Oldenburg was among the ships present during the celebration marking the event.

The majority of the exercises were focused in the Baltic, but the fleet did conduct maneuvers in the North Sea for eight days in September.

Oldenburg participated in the visit to Great Britain in August, where Wilhelm II took part in the Cowes Regatta.

After returning from the cruise in Scandinavian waters, Oldenburg and the rest of the division participated in the ceremonial transfer of the island of Helgoland from British to German control.

The visit lasted into early March, and while the ship was in Britain, a detachment of her crew was sent to participate in a military parade for Queen Victoria.

Oldenburg rejoined I Division on 1 May, and the year's maneuvers simulated a two-front war against Russia and either France or Denmark.

That year, the German fleet was reorganized and a training squadron of ironclads was kept in commission through the winter, though Oldenburg was assigned to the Reserve Division of the North Sea, at that time coming under the command of KzS Alfred Herz.

[15][16] The ship was reactivated in early 1892 and reassigned to I Division to participate in the normal routine of training exercises and voyages abroad.

She remained out of service for the next five years, before being reactivated on 1 October 1897 to replace the old ironclad König Wilhelm in II Division of I Battle Squadron.

On 1 December, she departed for the Mediterranean to join an international naval demonstration off the island of Crete, which Greece had sought to annex.

On the way there, Oldenburg was forced to stop in El Ferrol, Spain, to take on more coal, and she arrived Suda Bay, Crete, on 6 January 1898.

The ship remained in the demonstration until 16 March, when Germany and Austria-Hungary withdrew their naval contingents in a show of dissatisfaction over the compromise solution, which left Crete under Ottoman control, but with a Greek prince.

The ship was interrupted again while in Málaga, Spain, by the outbreak of the Spanish–American War; she was ordered to remain in the area in the event that Germany's ambassador had need of the vessel.

Oldenburg remained in Cadiz, Spain, from mid-April to mid-May; during this period, the ship's executive officer, Kapitänleutnant (Captain Lieutenant) Günther von Krosigk, was sent as a liaison with the Spanish naval command.

The ship later went to Lisbon, Portugal, for the celebration commemorating the 400th anniversary of the return of Vasco da Gama after his first voyage to India.

The ship rejoined II Division of I Squadron and took part in the annual training cycle for the rest of the year.

[18] On 22 March 1899, while steaming off Bülk in a heavy snow storm, Oldenburg ran aground and could not free herself, particularly after sand got into her condensers.

She was present for a celebration of the 50th anniversary of a battle during the First Schleswig War between German artillery batteries and Danish warships.