The U-3 class was a class

Ship class

A ship class is a group of ships of a similar design. This is distinct from a ship-type, which might reflect a similarity of tonnage or intended use. For example, the is a nuclear aircraft carrier of the Nimitz class....

 of two submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s or U-boats built for and operated by the Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

 . The U-3-class boats were designed and built by Germaniawerft

Friedrich Krupp Germaniawerft

Friedrich Krupp Germaniawerft was a German shipbuilding company, located in the harbour at Kiel, and one of the largest and most important builders of U-boats for the Kaiserliche Marine in World War I and the Kriegsmarine in World War II.-History:The company was founded in 1867 by Lloyd Foster, as...

 of Kiel

Kiel

Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

, Germany. The class was a part of the Austro-Hungarian Navy's efforts to competitively evaluate three foreign submarine designs.

The two U-3-class boats, both launched in 1908, were just under 140 feet (42.7 m) long and were each powered by two kerosene

Kerosene

Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...

 two-stroke engines while surfaced, and two electric motor

Electric motor

An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

s when submerged. The U-3 class initially had diving problems that were alleviated after several modifications to fins and diving plane

Diving plane

A diving plane, also known as a hydroplane, is a control surface found on submarines which allow the vessel to pitch its bow and stern up or down to assist in the process of submerging or surfacing the boat, as well as controlling depth when submerged....

s. Both boats of the class served in combat during World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. , the lead boat

Lead ship

The lead ship or class leader is the first of a series or class of ships all constructed according to the same general design. The term is applicable military ships and larger civilian craft.-Overview:...

 of the class, was sunk by gunfire in August 1915. was the longest-serving Austro-Hungarian submarine and sank over of ships, including the Italian armored cruiser Giuseppe Garibaldi

Italian cruiser Giuseppe Garibaldi (1899)

Giuseppe Garibaldi was the lead ship of her class of armoured cruisers for Italy's Regia Marina. The ship was launched on 29 June 1899 and served the Regia Marina until she was sunk by torpedoes from Austro-Hungarian Navy submarine on 18 July 1915, with loss of 57 lives.Garibaldis wreck is located...

 in July 1915. U-4 was handed over to France as a war reparation in 1920 and scrapped.

Design and construction

In 1904, after allowing the navies of other countries to pioneer submarine developments, the Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

 ordered the Austrian Naval Technical Committee (MTK) to produce a submarine design. The January 1905 design developed by the MTK and other designs submitted by the public as part of a design competition were all rejected by the Navy as impracticable. They instead opted to order two submarines each of designs by Simon Lake

Simon Lake

Simon Lake was a Quaker American mechanical engineer and naval architect who obtained over two hundred patents for advances in naval design and competed with John Philip Holland to build the first submarines for the United States Navy.Born in Pleasantville, New Jersey, Lake joined his father's...

, Germaniawerft

Friedrich Krupp Germaniawerft

Friedrich Krupp Germaniawerft was a German shipbuilding company, located in the harbour at Kiel, and one of the largest and most important builders of U-boats for the Kaiserliche Marine in World War I and the Kriegsmarine in World War II.-History:The company was founded in 1867 by Lloyd Foster, as...

, and John Philip Holland

John Philip Holland

John Philip Holland was an Irish engineer who developed the first submarine to be formally commissioned by the U.S...

 for a competitive evaluation. The two Germaniawerft submarines comprised the U-3 class.The Lake design became the U-1 class

U-1 class submarine (Austria-Hungary)

The U-1 class was a class of two submarines or U-boats built for and operated by the Austro-Hungarian Navy . The U-1-class boats were built to an American design at the navy yard in Pola...

 while the Holland design became the U-5 class

U-5 class submarine (Austria-Hungary)

The U-5 class was a class of three submarines or U-boats that were operated by the Austro-Hungarian Navy before and during World War I. The class was a part of the Austro-Hungarian Navy's efforts to competitively evaluate three foreign submarine designs....

. The Navy authorized two boats, U-3 and U-4, from the Germaniawerft in 1906.

The U-3-class was an improved version of Germaniawerft's design for the Imperial German Navy's first U-boat, , and featured a double hull

Submarine hull

The term light hull is used to describe the outer hull of a submarine, which houses the pressure hull, providing hydrodynamically efficient shape, but not holding pressure difference...

 with internal saddle tank

Saddle tank (submarine)

Saddle tanks are a type of ballast tank configuration fitted to mid-era submarines, those of World War II.Saddle tanks are fitted in pairs external to the pressure hull, one on each side, in a similar manner to that of a horse's saddle-bags, the positioning of which they resemble in appearance.-...

s. The Germaniawerft engineers refined the design's hull shape through extensive model trials. The boats were 138 in 9 in (42.29 m) long by 14 feet (4.3 m) abeam and had a draft of 12 in 6 in (3.81 m). Each boat displaced

Displacement (ship)

A ship's displacement is its weight at any given time, generally expressed in metric tons or long tons. The term is often used to mean the ship's weight when it is loaded to its maximum capacity. A number of synonymous terms exist for this maximum weight, such as loaded displacement, full load...

 240 tonnes (264.6 ST) surfaced and 300 tonnes (330.7 ST) submerged. Each submarine had two bow 45 centimetres (17.7 in) torpedo tubes, and was designed to carry up to three torpedoes.

and were both laid down on 12 March 1907 at Germaniawerft in Kiel and were launched in August and November 1908, respectively.In their book The German Submarine War, 1914–1918, R. H. Gibson and Maurice Prendergast report that both boats were launched in 1909 (p. 384). After completion, each was towed to Pola

Pula

Pula is the largest city in Istria County, Croatia, situated at the southern tip of the Istria peninsula, with a population of 62,080 .Like the rest of the region, it is known for its mild climate, smooth sea, and unspoiled nature. The city has a long tradition of winemaking, fishing,...

 via Gibraltar

Gibraltar

Gibraltar is a British overseas territory located on the southern end of the Iberian Peninsula at the entrance of the Mediterranean. A peninsula with an area of , it has a northern border with Andalusia, Spain. The Rock of Gibraltar is the major landmark of the region...

, with U-3 arriving in January 1909 and U-4 arriving in April.

Service career

Both boats were commissioned into the Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

 in 1909, with U-4 commissioned in August and U-3 in September. During the evaluations conducted by the Navy, the U-3 design bested the U-1

U-1 class submarine (Austria-Hungary)

The U-1 class was a class of two submarines or U-boats built for and operated by the Austro-Hungarian Navy . The U-1-class boats were built to an American design at the navy yard in Pola...

 (Lake) and U-5

U-5 class submarine (Austria-Hungary)

The U-5 class was a class of three submarines or U-boats that were operated by the Austro-Hungarian Navy before and during World War I. The class was a part of the Austro-Hungarian Navy's efforts to competitively evaluate three foreign submarine designs....

 (Holland) classes in reliability and provided the best living conditions. They did, however, have the worst diving abilities of the three designs, and produced excessive exhaust smoke.The results of the evaluation led the Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

 to order five new U-boats from Germaniawerft as the . To remedy the diving problems of the U-3-class, the fins were changed in size and shape several times. Eventually the front diving plane

Diving plane

A diving plane, also known as a hydroplane, is a control surface found on submarines which allow the vessel to pitch its bow and stern up or down to assist in the process of submerging or surfacing the boat, as well as controlling depth when submerged....

s were removed and a stationary stern flap was affixed to the hull.

From their commissioning to the outbreak of World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 1914, both U-3-class submarines served as training boats and sailed on as many as ten cruises a month in that capacity. At the beginning of the war, the U-3 boats made up half of the operational U-boats in the Austro-Hungarian Navy fleet. The armament of each boat was supplemented by the addition of a 3.7 centimetres (1.5 in) quick firing

Quick-firing gun

A quick-firing gun is an artillery piece, typically a gun or howitzer, which has several characteristics which taken together mean the weapon can fire at a fast rate...

 (QF) deck gun

Deck gun

A deck gun is a type of artillery cannon mounted on the deck of a ship or submarine.The deck gun was used as a defensive weapon against smaller boats or ships and in certain cases where torpedo use was limited. Typically a crew of three; gunner, loader, and layer, operated the gun, while others...

. Both boats conducted reconnaissance cruises for a large part of the first year of the war. In August 1915, U-3 was sunk by a French destroyer

Destroyer

In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

 after making an unsuccessful torpedo attack on an Italian armed merchant cruiser. U-4 went on to become the longest serving Austro-Hungarian submarine, sinking twelve ships that totaled over and damaging a British Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 cruiser.

SM U-3

SM U-3 was laid down on 12 March 1907 at Germaniawerft

Friedrich Krupp Germaniawerft

Friedrich Krupp Germaniawerft was a German shipbuilding company, located in the harbour at Kiel, and one of the largest and most important builders of U-boats for the Kaiserliche Marine in World War I and the Kriegsmarine in World War II.-History:The company was founded in 1867 by Lloyd Foster, as...

 in Kiel

Kiel

Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

 (work no. 135) and launched on 20 August 1908. Upon completion, she was towed via Gibraltar

Gibraltar

Gibraltar is a British overseas territory located on the southern end of the Iberian Peninsula at the entrance of the Mediterranean. A peninsula with an area of , it has a northern border with Andalusia, Spain. The Rock of Gibraltar is the major landmark of the region...

 to Pola

Pula

Pula is the largest city in Istria County, Croatia, situated at the southern tip of the Istria peninsula, with a population of 62,080 .Like the rest of the region, it is known for its mild climate, smooth sea, and unspoiled nature. The city has a long tradition of winemaking, fishing,...

, where she arrived on 24 January 1909. She was commissioned into the Austro-Hungarian Navy

Austro-Hungarian Navy

The Austro-Hungarian Navy was the naval force of Austria-Hungary. Its official name in German was Kaiserliche und Königliche Kriegsmarine , abbreviated as k.u.k. Kriegsmarine....

 on 12 September, and served as a training vessel through the beginning of World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. For most of the first year of the war, she conducted reconnaissance cruises from Cattaro. On 12 August 1915, U-3 made an unsuccessful torpedo attack on the Italian armed merchant cruiser  in the northern end of the Strait of Otranto

Strait of Otranto

The Strait of Otranto connects the Adriatic Sea with the Ionian Sea and separates Italy from Albania. Its width at Punta Palascìa, east of Salento is less than . The strait is named after the Italian city of Otranto.- History :...

 and was rammed and damaged by the Italian ship in return. U-3 succumbed to gunfire from the French destroyer Bisson the following day, with the loss of seven crewmen, including Linienschiffsleutnant Karl Strnad, her commanding officer; the other fourteen men of the crew were captured.

SM U-4

SM U-4 was laid down in March 1907 at Germaniawerft in Kiel (work no. 136) and launched in November 1908. Upon completion, she was towed via Gibraltar to Pola, where she arrived in January 1909. She was commissioned into the Austro-Hungarian Navy in August, and served as a training vessel through the beginning of World War I.

Over the first year of the war, U-4 made several unsuccessful attacks on warships and captured several smaller vessels as prize

Prize (law)

Prize is a term used in admiralty law to refer to equipment, vehicles, vessels, and cargo captured during armed conflict. The most common use of prize in this sense is the capture of an enemy ship and its cargo as a prize of war. In the past, it was common that the capturing force would be allotted...

s. In July 1915, she scored what Conway's All the World's Fighting Ships, 1906–1921 called her greatest success when she torpedoed and sank the Italian armored cruiser , the largest ship hit by U-4 during the war. In mid-May 1917, U-4 was a participant in a raid on the Otranto Barrage

Otranto Barrage

The Otranto Barrage was an Allied naval blockade of the Otranto Straits between Brindisi in Italy and Corfu on the Albanian side of the Adriatic Sea in World War I. The blockade was intended to prevent the Austro-Hungarian Navy from escaping into the Mediterranean and threatening Allied operations...

 which precipitated the Battle of Otranto Straits

Battle of the Strait of Otranto (1917)

The 1917 Battle of the Strait of Otranto was the result of an Austro-Hungarian raid on the Otranto Barrage, an Allied naval blockade of the Strait of Otranto. The battle took place on 14–15 May 1917, and was the largest surface action in the Adriatic Sea during World War I...

. In a separate action that same month, U-4 sank her second largest ship, the Italian troopship

Troopship

A troopship is a ship used to carry soldiers, either in peacetime or wartime...

 Perseo. She scored her final success in July 1917 with the sinking of a French tug

Tug

Tuğ is a village in the Khojavend Rayon of Azerbaijan....

. In total, U-4 sank twelve ships totaling . She survived the war as Austria-Hungary's longest serving submarine, was ceded to France as a war reparation, and scrapped in 1920.