Forel was a midget submarine

Midget submarine

A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 8, with little or no on-board living accommodation...

 built for the Imperial Russian Navy

Imperial Russian Navy

The Imperial Russian Navy refers to the Tsarist fleets prior to the February Revolution.-First Romanovs:Under Tsar Mikhail Feodorovich, construction of the first three-masted ship, actually built within Russia, was completed in 1636. It was built in Balakhna by Danish shipbuilders from Holstein...

 by Krupp

Krupp

The Krupp family , a prominent 400-year-old German dynasty from Essen, have become famous for their steel production and for their manufacture of ammunition and armaments. The family business, known as Friedrich Krupp AG Hoesch-Krupp, was the largest company in Europe at the beginning of the 20th...

 in Kiel, Germany. She was delivered to Russia in May 1904 as a gift fom the Krupp company after an order for 3 submarines for the Russian navy (Karp-type

Karp class submarine

The Karp Class were a group of submarines built by Krupp Germaniawerft for the Imperial Russian Navy. The boats were ordered in the 1904 emergency programme as a result of the Russo-Japanese War. The design was a twin hull type with 7 ballast tanks and a 16 fathom diving limit. The boats were...

, basis for the German U-1) and later shipped to Vladivostok

Vladivostok

The city is located in the southern extremity of Muravyov-Amursky Peninsula, which is about 30 km long and approximately 12 km wide.The highest point is Mount Kholodilnik, the height of which is 257 m...

 by rail at the time of the Russo-Japanese War

Russo-Japanese War

The Russo-Japanese War was "the first great war of the 20th century." It grew out of rival imperial ambitions of the Russian Empire and Japanese Empire over Manchuria and Korea...

. She was not successful and was decommissioned in 1911.