SM U-75 was one of the 329 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 serving in the Imperial German Navy (Kaiserliche Marine

Kaiserliche Marine

The Imperial German Navy was the German Navy created at the time of the formation of the German Empire. It existed between 1871 and 1919, growing out of the small Prussian Navy and Norddeutsche Bundesmarine, which primarily had the mission of coastal defense. Kaiser Wilhelm II greatly expanded...

) in 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...

.
U-75 was engaged in naval warfare

Naval warfare of World War I

Naval warfare in World War I was mainly characterized by the efforts of the Allied Powers, with their larger fleets and surrounding position, to blockade the Central Powers by sea, and the efforts of the Central Powers to break that blockade or to establish an effective blockade of the United...

 and took part in the First Battle of the Atlantic.

On her first mission U-75 laid the mine

Naval mine

A naval mine is a self-contained explosive device placed in water to destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel...

 that sank the cruiser during her voyage to Russia

Russian Empire

The Russian Empire was a state that existed from 1721 until the Russian Revolution of 1917. It was the successor to the Tsardom of Russia and the predecessor of the Soviet Union...

 carrying British Secretary of State for War

Secretary of State for War

The position of Secretary of State for War, commonly called War Secretary, was a British cabinet-level position, first held by Henry Dundas . In 1801 the post became that of Secretary of State for War and the Colonies. The position was re-instated in 1854...

 Lord Kitchener

Herbert Kitchener, 1st Earl Kitchener

Field Marshal Horatio Herbert Kitchener, 1st Earl Kitchener KG, KP, GCB, OM, GCSI, GCMG, GCIE, ADC, PC , was an Irish-born British Field Marshal and proconsul who won fame for his imperial campaigns and later played a central role in the early part of the First World War, although he died halfway...

. The cruiser sank at 59°07′N 03°24′W west of the Orkney Islands

Orkney Islands

Orkney also known as the Orkney Islands , is an archipelago in northern Scotland, situated north of the coast of Caithness...

with heavy loss of life in a force 9 gale.