German Type U 139 submarine

U-139, originally designated "Project 46", was a class of large, long-range U-boats built during World War I by the Kaiserliche Marine.

Description
Three large U-cruisers, designated Type 139, were ordered from Germaniawerft, Kiel, in August 1916. Displacing nearly 2,000 tons, and with a surface speed of 15 kn, they were armed with 24 torpedoes and two 15 cm deck guns, and had a cruising range of around 12000 mi. They carried a large enough complement to furnish captured vessels with prize crews and their intended purpose was to capture or destroy merchantmen on the surface; their large-calibre deck guns and comparatively high speed allowed them to engage even armed merchant vessels.

Unlike the earlier Type U-151 submarines, the Type 139 was designed from the outset for war service. Four bow and two stern torpedo tubes were fitted, but the main armament was the two 15 cm deck guns, which could be laid by a rangefinder on the aft section of the bridge. The conning tower's command centre was protected by 90mm armour against the guns typically carried by enemy merchant ships, while the pressure hull was thicker than usual at 25mm, so as to increase diving depth. The superstructure was also raised by 2m so that a shell hitting it would not penetrate the pressure hull.

A Type 139 U-boat cost 8.7 million Marks at the time, the 150 mm guns accounting for around 7% of the cost. Three submarines of this type, U-139, U-140, and U-141, were ordered.

The later "Project 46(a)" specified even more powerful U-cruisers, of a similar displacement to the Type 139 boats, but with an increased surface speed of 18 kn, and with two 88mm deck guns in addition to the two 150mm guns.

An even larger U-cruiser was proposed under "Project 47", but never reached construction; it would have displaced 2,500 tons, had a top speed of 21 kn, and been armed with four 150mm guns as well as 6 torpedo tubes, 2 of which would have fired to the side.

Service
The Type 139 submarines were dispatched on long-range missions, south across the Equator, and to the west across the Atlantic, operating independently.

The famous Lothar von Arnauld de la Perière commanded U-139, the first of the class, and named the submarine Korvettenkapitän Schweiger, after Walther Schwieger, who had sunk the RMS Lusitania in 1915. Under von Arnauld, U-139 sank 5 small ships from May 1918, and sank the last ship to fall to a U-boat in World War I on 1 October 1918.

List of Type U 139 submarines
Three Type U 139 submarines were built, all of which were commissioned into the Kaiserliche Marine.


 * SM U-139 (Korvettenkapitän Schweiger)
 * SM U-140 (Kapitän Weddigen)
 * SM U-141