Irene-class cruiser

The Irene class was a class of protected cruisers built by the German Imperial Navy (Kaiserliche Marine) in the late 1880s. The class comprised two ships, SMS Irene and SMS Prinzess Wilhelm; they were the first protected cruisers built by the German Navy. As built, the ships were armed with a main battery of fourteen 15 cm guns and had a top speed of 18 kn. They were modernized in 1899–1905, and their armament was upgraded with new, quick-firing guns.

Both ships served in the East Asia station with the East Asia Squadron; Prinzess Wilhelm played a major role in the seizure of the Kiautschou Bay concession in November 1897. Both ships returned to Germany at the turn of the 20th century, and remained in European waters until 1914, when they were removed from active service. They were reduced to secondary roles then, and continued to serve until the early 1920s, when they were sold for scrap.

General characteristics
The ships were 98.9 m long at the waterline and 103.7 m long overall. They had a beam of 14.2 m and a draft of 6.74 m forward. They displaced 4271 MT at designed displacement and 5027 MT at full combat load. The hull was constructed with transverse and longitudinal steel frames, and the outer hull consisted of wood planking covered with Muntz copper sheathing to prevent fouling. The stem was made of bronze below and iron above. The hull was divided into 10 watertight compartments and had a double bottom that extended for 49 percent of the length of the hull.

The ships were very good sea boats; they ran very well before the wind, and were very handy. They lost minimal speed in hard turns and suffered from moderate roll and pitch. In heavy seas, the ships were capable of only half speed, as both suffered from structural weakness in the forecastle. They had a transverse metacentric height of .69 to .72 m. The ships had a crew of 28 officers and 337 enlisted men; after their modernization after the turn of the century, the ships' crews comprised 17 officers and 357 enlisted men. The ships carried a number of smaller boats, including two picket boats, one pinnace, two cutters, one yawl, and two dinghies. Searchlight platforms were added to the foremast 13 m above the waterline.

Machinery
Irene's propulsion system consisted of two horizontal Wolfsche 2-cylinder double-expansion steam engines powered by four coal-fired cylindrical double-boilers. Prinzess Wilhelm's engines were produced by AG Germania. Irene was equipped with a pair of three-bladed screws 4.5 m in diameter; Prinzess Wilhelm had slightly larger 4.7 m screws with four blades. The ships' engines were rated at 8000 ihp and provided a top speed of 18 kn and a range of approximately 2490 nmi at 9 kn. The ships were equipped with a pair of electrical generators that produced 23 kW at 67 volts. Prinzess Wilhelm was later equipped with three generators with a combined output of 33 kW at 110 volts. Steering was controlled by a single rudder.

Armament and armor
The ships were armed with four 15 cm K L/30 guns in single pedestal mounts, supplied with 400 rounds of ammunition in total. They had a range of 8500 m. The ships also carried ten shorter-barreled 15 cm K L/22 guns in single mounts. These guns had a much shorter range, at 5400 m. The gun armament was rounded out by six 3.7 cm revolver cannon. They were also equipped with three 35 cm torpedo tubes with eight torpedoes, two launchers were mounted on the deck and the third was in the bow, below the waterline. The ships were modernized in Wilhelmshaven between 1899 and 1905. The ships' armament was significantly improved; the four L/30 guns were replaced with a new model with an increased range of 10000 m. Eight 10.5 cm SK L/35 quick-firing (QF) guns were installed in place of the L/22 guns, and six 5 cm SK L/10 QF guns were added.

The ships were protected with compound steel armor. The armored deck was 20 mm plus 30 mm thick with 20 mm thick slopes. The coaming was 120 mm thick on 200 mm thick teak. The conning tower had 50 mm thick sides and a 20 mm thick roof. The ships were equipped with cork cofferdams.

Service history
Irene was the first protected cruiser built by the German navy. She was ordered under the contract name "Ersatz SMS Elisabeth" and was laid down at the AG Vulcan shipyard in Stettin in 1886. She was launched on 23 July 1887, after which fitting-out work commenced. She was commissioned into the German navy on 25 May 1888. Prinzess Wilhelm was ordered under the contract name "Ersatz SMS Ariadne (1871)" and was laid down at the Germaniawerft shipyard in Kiel in 1886. She was launched on 22 September 1887, after which fitting-out work commenced. She was commissioned into the German navy on 13 November 1889.

Both Irene and Prinzess Wilhelm saw extensive service with the German fleet. Irene frequently escorted Kaiser Wilhelm II's yacht on cruises throughout Europe. In 1894, Irene was deployed to East Asian waters; Prinzess Wilhelm joined her the following year. Prinzess Wilhelm was one of three ships involved in the seizure of the naval base Kiaochou Bay in November 1897, led by Admiral Otto von Diederichs. Irene was in dock for engine maintenance at the time, and so she was not present during the operation. As a result of the seizure, the Cruiser Division was reorganized as the East Asia Squadron. Both ships were present in the Philippines in the immediate aftermath of the Battle of Manila Bay between American and Spanish squadrons during the Spanish-American War in 1898. Diederichs hoped to use the crisis as an opportunity to seize another naval base in the region, though this was unsuccessful.

Prinzess Wilhelm returned to Germany in 1899 and was modernized in 1899–1903. Irene followed her sister back to Germany in 1901, and was similarly modified in 1903–1905. Both ships remained in service until early 1914, when they were retired from front-line service and used for secondary duties. Irene was converted into a submarine tender. She served in this capacity until 1921, when she was sold for scrap and broken up the following year. Prinzess Wilhelm was reduced to a mine hulk in February 1914 and ultimately broken up for scrap in 1922.