SMS Kaiserin und Königin Maria Theresia ("Empress and Queen Maria Theresa") was an armored cruiser used by the imperial Austro-Hungarian Navy from 1895 to 1917; she was the first ship of that type built by the Austro-Hungarian Navy. The ship was a unique design, built by the Stabilimento Tecnico Triestino shipyard in Trieste; she was laid down in July 1891, launched in April 1893, and completed in November 1894. Armed with a main battery of two 24-centimeter (9.4 in) guns and eight 15 cm (5.9 in) guns, the ship provided the basis for two subsequent armored cruiser designs for the Austro-Hungarian Navy.
In 1898, Kaiserin und Königin Maria Theresia was deployed to the Caribbean to safeguard Austro-Hungarian interests during the Spanish–American War; she inadvertently arrived off Santiago de Cuba on the morning the Spanish squadron attempted to escape from the American blockade, and was nearly attacked herself. In 1900, she was sent to China to assist in the suppression of the Boxer Rebellion, and remained in East Asian waters until 1902. She was heavily modernized between 1906 and 1910, and served in the 1st Cruiser Division after returning to the fleet. She was used first as a harbor guard ship and then as a barracks ship during World War I. After the end of the war, she was surrendered to Britain as a war prize and broken up for scrap in 1920.
In the 1890s, the Austro-Hungarian Navy began building large, modern cruisers, beginning with the protected cruisers of the Kaiser Franz Joseph I class. The Marinesektion, the executive committee of the Navy, decided to follow the Kaiser Franz Joseph I-class ships with a more powerful vessel, a larger, better armed armored cruiser, as the type had begun to gain prominence in foreign navies. The Austro-Hungarians requested design proposals from five British shipyards, though none of them were awarded the contract. The Navy gave the contract for "torpedo-ram cruiser C", as it was provisionally titled, to Stabilimento Tecnico Triestino, the Austrian dockyard in Trieste. The two subsequent armored cruisers, Kaiser Karl VI and Sankt Georg, were improved versions of this design.
Kaiserin und Königin Maria Theresia was 111.67 meters (366.4 ft) long at the waterline and 113.7 m (373 ft) long overall. She had a beam of 16.25 m (53.3 ft) and a draft of 6.81 m (22.3 ft). As designed, the ship displaced 5,330 metric tons (5,250 long tons; 5,880 short tons), and at full load she displaced 6,026 t (5,931 long tons; 6,643 short tons). She had a crew of 475 officers and men. The ship was powered by two 3-cylinder, horizontal triple expansion engines rated at 9,755 indicated horsepower (7,274 kW). This gave the ship a top speed of 19.35 knots (35.84 km/h; 22.27 mph).
Kaiserin und Königin Maria Theresia was armed with a main battery of two 24 cm K L/35 guns, manufactured by Krupp, and mounted in two single turrets, one forward and one aft. These guns were the primary offensive armament. For defense against torpedo boats, she also carried eight Krupp 8 cm SK L/35 guns, twelve Skoda 4.7 cm SK L/44 guns, six Hotchkiss 47 mm L/33 guns, and a pair of 7 cm L/15 landing guns; these guns were primarily mounted in casemates or sponsons. The landing guns could be taken ashore to provide support for a landing party. Her armament was rounded out by four 45 cm (18 in) torpedo tubes, one in the bow, one in the stern, and one on each side. Both the main battery turrets and the armored belt were protected by 100 mm (3.9 in) thick steel armor. The main deck was 38 to 57 mm (1.5 to 2.2 in) thick. The casemates were armored with 80 mm (3.1 in) of steel, and the conning tower had 50 mm (2.0 in) thick sides.
Kaiserin und Königin Maria Theresia was laid down on 1 June 1891, launched on 29 April 1893, and commissioned into the fleet in November 1894. In 1895, Archduke Charles Stephen of Austria took a squadron of warships, including Kaiserin und Königin Maria Theresia, to Germany to participate in the celebrations for the opening of the Kiel Canal. The squadron called on the port of Brest, France on the way, and stopped in Portsmouth on the return voyage. In early 1897, the ship joined the massive international fleet that demonstrated off Crete to protest the Greek annexation of the island from the Ottoman Empire. The Austro-Hungarian fleet was the third largest contingent, after the Italians and British. The Austro-Hungarians and Germans were dissatisfied with the compromise worked out, and so withdrew their contingents early, in March 1898.
In 1898, Kaiserin und Königin Maria Theresia was dispatched to Cuba during the Spanish–American War, to evacuate Austrian and German nationals in the city of Santiago. The ship arrived off Santiago on 3 July, the day the Spanish admiral Pascual Cervera y Topete attempted to break out of the harbor, through the American blockade. The American auxiliary vessel USS Resolute spotted Kaiserin und Königin Maria Theresia approaching US Army transports off Siboney and Daiquirí. Resolute informed the battleship USS Indiana about a "Spanish battleship" attacking the army ships, after which Indiana steamed to engage the supposed Spanish warship. After closing to 6,000 yards (5,500 m), Indiana's captain identified Kaiserin und Königin Maria Theresia shortly before his gunners would have opened fire. The Austrian cruiser had similar run-ins with other vessels of the American fleet as it sought permission from the American commander to perform its evacuation. After inspecting her, Admiral William T. Sampson, the American commander, permitted the Austrian cruiser to enter the harbor for her mission. After picking up the evacuees, Kaiserin und Königin Maria Theresia went to Port Royal, Jamaica, and remained in the Caribbean until the end of the war. On 9 May, she departed, bound for Pola, and arrived on 9 December. Over the winter of 1898–1899, the ship served in the winter training squadron along with the battleship Budapest.
As anti-foreign violence began to rise in China in early 1900, the Great Powers began to send warships to the Far East to increase the pressure on the Chinese government to reign in the violence. At the peak of the Boxer Rebellion, Kaiserin und Königin Maria Theresia was deployed to the area under the command of Victor Ritter Bless von Sambuchi, along with numerous other European warships. She left Pola in June, and was followed by the cruisers Kaiserin Elisabeth and Aspern the next month. The ships joined the international fleet off Taku in September 1900, though by that time, most of the fighting had already occurred. Nevertheless, Kaiserin und Königin Maria Theresia and Aspern remained in East Asian waters for an extended deployment. Captain Anton Haus took command of the ship, and in June 1901, he took the ship to Hankow up the Yangtze River; she was the largest ship to have steamed that far up the river. She returned to Austria-Hungary in 1902, and was replaced in China by the new armored cruiser Kaiser Karl VI.
Between 1906–1908 and 1909–1910, the ship was rebuilt and equipped with more modern main guns. The 24 cm guns were replaced with quick-firing 19 cm L/42 guns manufactured by Skoda. Four 37 mm Vickers revolving cannon were also installed. The ship's heavy fighting masts were removed. In 1912, the ship was sent to Salonika to safeguard Austro-Hungarian interests during the Balkan Wars. She was then assigned to the 1st Cruiser Division, and remained in that unit after the outbreak of World War I in August 1914. It consisted of the other two armored cruisers in the fleet, and three light cruisers, under the command of Vice Admiral Paul Fiedler. She was used as a harbor guard ship in Šibenik starting in 1914. In 1916, she was withdrawn from service and disarmed the following year for use as a barracks ship for German U-boat crews operating out of the Austrian naval base at Pola. Her guns were converted for use on land and sent to the Italian front. After the end of the war, in 1920, Kaiserin und Königin Maria Theresia was allocated to Britain as a war prize. The British sold her to an Italian ship-breaking firm, which broke her up for scrap.