Kaiser Friedrich III-class battleship

SMS Kaiser Barbarossa as completed, showing the short military masts and small bridge that distinguished the last three members of the class from the first two vessels

The Kaiser Friedrich III-class ships were 120.9 meters (396 ft 8 in) long at the waterline and 125.3 m (411 ft 1 in) overall. They had a beam of 20.4 m (66 ft 11 in) and a draft of 7.89 m (25 ft 11 in) forward and 8.25 m (27 ft 1 in) aft. The ships displaced 11,097 t (10,922 long tons) normally and up to 11,785 metric tons (11,599 long tons) at full load. The ships' steel hulls were of transverse and longitudinal frame construction. The hull contained twelve watertight compartments and a double bottom that covered 70 percent of the hull.[6] Kaiser Friedrich III was completed with a tall military mast for her foremast and a pole mainmast. The other four vessels were fitted with short military masts for both masts. In 1901, Kaiser Friedrich III's foremast was shortened. Kaiser Friedrich III and Kaiser Wilhelm II, both intended to serve as flagships, were completed with large bridges, with a two-story bridge aboard the former and a single-story bridge on the latter. The remaining three vessels received smaller, open bridges.[7]

The German navy regarded them as having excellent seakeeping. They had a tight turning circle and were very responsive. The ships rolled up to 15° and had a roll period of 12 seconds. They suffered only minor speed loss in heavy seas, but up to 40 percent with the rudder hard over. Their metacentric heights were between 0.917 to 1.18 m (3 ft 0 in to 3 ft 10 in). The ships carried a number of smaller boats, including two picket boats, two launches, one pinnace, two cutters, two yawls, and two dinghies. The crew numbered 39 officers and 612 enlisted men. When serving as a squadron flagship, a ship had its crew augmented by another 12 officers and between 51 and 63 enlisted men.[6]

The Kaiser Friedrich III-class battleships were powered by three 3-cylinder vertical triple-expansion steam engines that drove three screws. Kaiser Friedrich III, Kaiser Barbarossa, and Kaiser Wilhelm der Grosse were equipped with three 3-bladed screws that were 4.5 m (14 ft 9 in) in diameter. Kaiser Karl der Grosse and Kaiser Wilhelm II were equipped with two of the 3-bladed screws on the outer shafts and a four-bladed screw that was 4.2 m (13 ft 9 in) in diameter on the center shaft. The ships received different boiler arrangements owing to concerns among the naval high command about the reliability of the new water-tube boilers. Kaiser Wilhelm II had an arrangement similar to Kaiser Friedrich III, except the Thornycroft boilers were replaced by Marine-type fire-tube boilers. Kaiser Wilhelm der Grosse and Kaiser Karl der Grosse were equipped with four Marine and six cylindrical fire-tube boilers, while Kaiser Barbarossa had four Thornycroft and six cylindrical fire-tube boilers. All of the ships' boilers were ducted into two funnels, but Kaiser Friedrich III and Kaiser Wilhelm II had thinner aft funnels while those of the other three ships were identical.[6][8]

The powerplants were rated at 13,000 metric horsepower (12,820 ihp; 9,560 kW), but on trials could produce up to 13,950 metric horsepower (13,760 ihp; 10,260 kW). This generated a top speed of 17.5 knots (32.4 km/h; 20.1 mph). The ships carried 650 metric tons (640 long tons) of coal, although the use of additional spaces within the ships increased fuel capacity to 1,070 metric tons (1,050 long tons). This provided a maximum range of 3,420 nautical miles (6,330 km; 3,940 mi) at a cruising speed of 10 knots (19 km/h; 12 mph). Electrical power was supplied by five 320 kW 74 volt generators in Kaiser Friedrich III and Kaiser Wilhelm II, and four 240 kW 74 volt generators in the other three ships.[6]

Forward guns on one of the Kaiser Friedrich III-class ships

The primary armament consisted of a battery of four 24 cm (9.4 in) SK L/40 guns in twin-gun turrets,[lower-alpha 1] one fore and one aft of the central superstructure. The guns were mounted in hydraulically-operated Drh.L. C/98 turrets, which allowed elevation to +30 degrees and depression to −5 degrees. At maximum elevation, the guns could hit targets out to 16,900 meters (18,500 yd). The guns fired 140-kilogram (310 lb) shells at a muzzle velocity of 835 meters per second (2,740 ft/s). Each gun was supplied with 75 shells, for a total of 300.[10][11]

Secondary armament included eighteen 15 cm (5.9 inch) SK L/40 guns. Six were mounted in single turrets amidships and the rest were mounted in MPL casemates; all were manually operated and elevated.[lower-alpha 2] Most of these guns were mounted at upper-deck level, with only four of the casemates at main deck level, which kept them high enough in the ship to avoid a common problem with battleships of the period where heavy seas could make the guns unworkable. According to the historian Aidan Dodson, the arrangement was "perhaps the best of the period."[12] These guns fired armor-piercing shells at a rate of 4 to 5 per minute. The ships carried 120 shells per gun, for a total of 2,160 rounds total. The guns could depress to −7 degrees and elevate to +20 degrees, for a maximum range of 13,700 m (14,990 yd). The shells weighed 51 kg (112 lb) and were fired at a muzzle velocity of 735 m/s (2,410 ft/s).[11][13]

The ships also carried twelve 8.8 cm (3.45 in) SK L/30 quick-firing guns for defense against torpedo boats,[6] also mounted individually in casemates and pivot mounts. These guns were supplied with between 170 and 250 shells per gun. These guns fired 7.04 kg (15.5 lb) shell at a muzzle velocity of 590 mps (1,936 fps). Their rate of fire was approximately 15 shells per minute; the guns could engage targets out to 6,890 m (7,530 yd). The gun mounts were manually operated.[11][14] The ships' gun armament was rounded out by twelve 3.7 cm (1.5 in) Maxim machine cannon.[6]

The ships were also armed with six 45 cm (17.7 in) torpedo tubes, all in above-water swivel mounts. Four tubes were mounted on the sides of the ship, another in the bow, and the last in the stern.[6] These weapons were 5.1 m (201 in) long and carried an 87.5 kg (193 lb) TNT warhead. They could be set at two speeds for different ranges. At 26 knots (48 km/h; 30 mph), the torpedoes had a range of 800 m (870 yd). At an increased speed of 32 knots (59 km/h; 37 mph), the range was reduced to 500 m (550 yd).[15]

The Kaiser Friedrich III-class ships were armored with steel produced by Krupp. They were the last German capital ships to use the old-style narrow armor belt arrangement; older compound armor required a significant amount of steel to resist large-caliber shellfire, which meant that little of the ship could be covered with armor owing to its weight. Krupp's new steel was much stronger, but the design staff did not take advantage of the reduced weight to provide more comprehensive protection, which would arrive with the subsequent Wittelsbach class.[1]

They had an armor belt that was 300 millimeters (11.8 in) thick in the central portion of the hull at the waterline. It tapered to 150 mm (5.9 in) in the forward section and 200 mm (7.9 in) in the rear, although the belt did not extend fully aft. The lower portion of the belt ranged in thickness from 100 to 180 mm (3.9 to 7.1 in). The entire belt was backed with 250 mm (9.8 in) of teak. The main armored deck was 65 mm (2.6 in) thick,[6] but the thickness was increased to 75 mm (3 in) aft of the rear main battery barbette, where the stern was not protected by the belt. This portion of the deck curved down at the sides to offer a measure of protection against shell hits.[16]

The conning tower was protected by armored sides that were 250 mm thick and a roof that was 30 mm (1.2 in) thick. Each main-battery turret had a 50 mm (2 in) thick roof and 250 mm thick sides. The 15 cm guns mounted in turrets were protected by 150 mm thick sides and 70 mm (2.8 in) thick gun shields. Those in the casemates also had 150 mm worth of armor protection.[6]

Lithograph of Kaiser Friedrich III in 1902

On entering service, Kaiser Friedrich III became the flagship of Prince Heinrich, the commander of I Squadron of the Home Fleet. Kaiser Wilhelm II became the flagship of Koester, the fleet commander. The two ships operated together into early 1901 until Kaiser Friedrich III was badly damaged in a grounding accident while cruising in the Baltic Sea in April. An investigation revealed several uncharted rocks and faulted the lightship in the area, which was out of position. While she was out of service for repairs, her crew was transferred to Kaiser Wilhelm der Grosse, which had just been completed. Over the course of the next four years, the ships of the class operated together in I Squadron, conducting training cruises, fleet maneuvers every August and September, and visits to foreign ports.[19]

By 1905, as several new classes of battleships—the Wittelsbach, Braunschweig, and Deutschland classes—had either entered service or were approaching completion, the members of the Kaiser Friedrich III class began to be transferred to II Squadron. In 1906, Kaiser Wilhelm II was replaced as the fleet flagship by the new battleship Deutschland. The normal peacetime training routine continued for the next several years, interrupted by a reconstruction program in the mid to late-1900s. Kaiser Barbarossa was the first to be rebuilt in 1905, a result of having been decommissioned for repairs to her rudder for damage incurred on a cruise to Spain in 1903. Kaiser Friedrich III was rebuilt in 1907, Kaiser Wilhelm II and Kaiser Wilhelm der Grosse were reconstructed in 1909–1910.[20] The work involved cutting down their superstructure to reduce topweight, removing four of the 15 cm guns and one of the torpedo tubes, and moving the 8.8 cm guns to the upper deck.[21] Kaiser Karl der Grosse was not modernized, however.[6]

Beginning in 1908, the members of the class transitioned out of front-line service, their place having been taken by the Deutschland class and the first dreadnought battleships of the Nassau class. Kaiser Karl der Grosse was the first to be moved to the Reserve Squadron in 1908, followed by Kaiser Barbarossa and Kaiser Friedrich III in 1909 and Kaiser Wilhelm II and Kaiser Wilhelm der Grosse the next year. For the rest of their peacetime careers, they spent much of the year out of service but were reactivated for the annual fleet maneuvers every August and September. For the exercises, they formed III Squadron, with Kaiser Wilhelm II serving as the squadron flagship.[22]

Kaiser Barbarossa after her reconstruction

Following the outbreak of World War I in July 1914, the five Kaiser Friedrich III-class ships were reactivated to form V Battle Squadron, with Kaiser Wilhelm II again as the flagship. They served briefly in a coastal-defense role in the North Sea before being transferred to the Baltic in September for operations against the Russian Empire. They were slated to carry an amphibious assault force to Windau in late September, but false rumors of British warships having entered the Baltic led to the operation being cancelled. They made a sweep into the northern Baltic in December but did not encounter any Russian warships. In January 1915, they were moved back to the North Sea for guard duties, but they were quickly decommissioned the next month. The ships were by then thoroughly obsolete and were far too vulnerable to modern weapons, particularly the British submarines that had begun operating in the Baltic. In addition, the navy was facing severe crew shortages and decided that older vessels of limited combat use like the Kaiser Friedrich III class could not be maintained in service.[23]

On 5 March, the ships were dispersed to various ports, had their crews reduced, and were eventually disarmed. Kaiser Wilhelm II was stationed in Wilhelmshaven as a headquarters ship for the commander of the High Seas Fleet, a role she continued to fill after the war. Kaiser Karl der Grosse was used briefly as an engine-room training ship before being converted into a prison ship; Kaiser Friedrich III and Kaiser Barbarossa also served as floating prisons in Kiel and Wilhelmshaven, respectively. Kaiser Wilhelm der Grosse became a depot ship before being relegated to a torpedo target ship in 1916.[24][25] The guns taken from the ships were used as coastal artillery in the North Frisian and East Frisian Islands in the North Sea and to guard Libau in the Baltic.[10] All five ships were broken up between 1920 and 1922 after the end of the war to ensure Germany complied with the naval disarmament clauses of the Treaty of Versailles. The bow ornaments from Kaiser Friedrich III and Kaiser Wilhelm II are preserved at the Militärhistorisches Museum der Bundeswehr in Dresden.[25]