SMS Ägir[a] was the second and final member of the Odin class of coastal defense ships (Küstenpanzerschiffe) built for the Imperial German Navy.

General Leo von Caprivi, the new Chef der Admiralität (Chief of the Admiralty), was able to secure approval from the Reichstag (Imperial Diet) for ten small coastal defense ships, the first six of which became the Siegfried class, which carried three main battery guns in individual barbette mounts.

Proposals for the last four included redesigning the vessels to add another main battery gun in two-gun turrets came to nothing owing to the cost of other naval programs—most notably the Brandenburg-class battleships.

The two Odin-class ships were ultimately built to a modified version of the Siegfried design that incorporated improvements to the armor layout and other minor changes.

Ägir also carried three 45 cm (17.7 in) torpedo tubes, two in swivel mounts on the deck amidships and one in the bow, submerged below the waterline.

[5][6] The ship conducted shooting practice in 1898 and participated in the annual training maneuvers with the rest of the German fleet in August and September.

During the exercises, which were held in the Baltic and North Seas, she served as the flagship of II Battle Squadron, which was temporarily formed for the maneuvers.

[6] From late April to 31 May 1899, Ägir was activated for operations with I Battle Squadron in place of the armored corvette Oldenburg, which had accidentally run aground and needed repairs.

Ägir participated in a cruise with the rest of the squadron to Britain, where they represented Germany at an international fleet review held for Queen Victoria's 80th birthday.

During a cruise in the Kattegat in June, Ägir was among the vessels that came to the assistance of the Norddeutscher Lloyd steamship SS Kaiserin Maria Theresia, which had run aground.

During the fleet maneuvers that year, Ägir served as the flagship of IV Division, II Squadron, under the command of KAdm Conrad von Bodenhausen.

Aberfoyle struck Ägir below her forward main battery gun on the starboard side below the waterline in the accident, causing a serious leak.

[6] On 2 June, Ägir and Odin assisted the passenger liner SS Deutschland, which had run aground in the Stettiner Haff.

She continued to operate with the Reserve Division in 1901, and during its active period, the squadron was commanded by KAdm Hugo von Schuckmann, who flew his flag aboard Ägir.

While on divisional exercises in the Strander Bucht on 6 August, Ägir suffered a boiler room fire that badly injured five crewmen.

KK von Witzleben replaced Gerdes after the maneuvers, and in October, Ägir embarked on a training cruise in the western Baltic along the coast of East Prussia.

On 2 April, after a cruise in the Baltic, Ägir stopped in Danzig, where her crew assisted in the suppression of a fire at the Klawitter shipyard.

In June and July, Ägir joined the fleet for a summer cruise to visit numerous ports in Norway, Sweden, and Denmark.

She was recommissioned on 12 August and assigned to VI Battle Squadron with the other seven coastal defense ships of the Odin and Siegfried classes.

The ships of VI Squadron conducted readiness training for the next month, and on 14 September they were transferred to the North Sea to guard Germany's coast.

For the next several months, the ships alternated between the mouth of the Weser river and Jade Bay, the latter being the location of Germany's primary naval base in the North Sea, Wilhelmshaven.

Two salvage boats quickly reached her, but as she was firmly lodged on the shallows the captain turned them down and preferred to wait for assistance from Germany.