SM U-117

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SM U-117 at Cape Charles
SM U-117 at Cape Charles
German Empire
Name: U-117
Builder: AG Vulcan Stettin
Laid down: 1917
Launched: 10 December 1917
Commissioned: 28 March 1918
Homeport: Kiel
  • Surrendered, 21 November 1918
  • Taken over by the US Navy, 1919
United States
Name: USS U-117
Acquired: March 1919
Fate: Sunk as a target, 22 June 1921
General characteristics [1]
Class and type: German Type UE II submarine
Type: Coastal minelaying submarine
  • 1,164 t (1,146 long tons) surfaced
  • 1,512 t (1,488 long tons) submerged
Length: 81.52 m (267 ft 5 in) (o/a)
Beam: 7.42 m (24 ft 4 in)
Height: 10.16 m (33 ft 4 in)
Draught: 4.22 m (13 ft 10 in)
Installed power:
Propulsion: 2 shafts, 2 × 1.61 m (5 ft 3 in) propellers
  • 14.7 knots (27.2 km/h; 16.9 mph) surfaced
  • 7 knots (13 km/h; 8.1 mph) submerged
  • 13,900 nmi (25,700 km; 16,000 mi) at 8 knots (15 km/h; 9.2 mph) surfaced
  • 35 nmi (65 km; 40 mi) at 4.5 knots (8.3 km/h; 5.2 mph) submerged
Test depth: 75 m (246 ft)
Complement: 4 officers, 36 enlisted
Service record
Commanders: Kptlt. Otto Dröscher
Operations: 1 war patrol
  • 21 ships sunk 27,494 GRT
  • 2 ships damaged 7,535 GRT
  • 1 warship damaged (18,000 tons)

SM U-117 was a Type UE II long-range minelayer submarine of the Imperial German Navy. It was laid down in 1917 at Hamburg, Germany, by Aktiengesellschaft Vulcan and launched on 10 December 1917. It was commissioned in the Imperial German Navy on 28 March 1918 with Kapitänleutnant Otto Dröscher in command. After shakedown, U-117 was posted to the U-Kreuzer Verband (submarine cruiser unit) on 1 June 1918. Over the next five weeks, she completed fitting out at Kiel.

Service history[edit]

Operations off North America[edit]

On 11 July, U-117 departed Kiel and took the eastern route through the Baltic Sea around Denmark and out into the North Sea by way of the Skagerrak. After rounding the Shetland Islands, she set a course for the coast of North America to lay minefields off the coast of the United States and to conduct cruiser warfare. During the voyage across the Atlantic, heavy weather foiled her attempts to attack two lone steamers, two convoys, and a small cruiser.

U-117 reached the American coastal zone on 8 August 1918, and her fortunes improved soon thereafter. On 10 August, she encountered a fleet of fishing craft and went on a spree, sinking nine of the vessels with explosives and gunfire. On the 12th, she sighted the ballast-laden steamer Sommerstadt and, after observing that the Norwegian steamer was armed, made a submerged attack that sank her with a single torpedo. The following day, the U-boat made another submerged torpedo attack and hit the 7,127-ton American tanker Frederick R. Kellogg, bound from Tampico, Mexico, to Boston, Massachusetts, with 7,500 barrels of crude oil. The action occurred only 12 miles north of Barnegat Light, New Jersey; however, Kellogg was disabled in such shallow water that the Americans were able to salvage her.

Later that same day, the minelayer submarine began the other half of her duty by laying mines near Barnegat Light. The effort subsequently bore fruit when the Mallory Line steamship San Saba struck a mine and sank on 4 October 1918. On 14 August, U-117 took a break from mining operations to resume cruiser warfare when she encountered an American schooner. The U-boat brought her deck guns to bear on the sailing vessel and sank her. Shortly thereafter, however, the hunter became the hunted when an American seaplane forced the submarine to seek refuge beneath the surface. The aircraft and submarine chaser SC-71 subjected U-117 to a brief barrage of bombs, and SC-71 attacked the submarine with depth charges before losing track of her.

The next day, 15 August 1918, U-117 resumed her mine laying operations off Fenwick Island Lightship. That field later claimed two victims, one damaged and the other sunk. On 29 September 1918, USS Minnesota struck one of those mines and suffered extensive damage. The Naval Overseas Transportation Service cargo ship Saetia (Id. No. 2317) entered the same field on 9 November, struck a mine, and sank. Later that day — still 14 August — the submarine moved farther south and, after laying a third minefield near Winter Quarters Shoal Lightship, halted an American sailing vessel, the 1,613-ton Madrugada, and sank her with gunfire. A patrolling American seaplane foiled a subsequent attempt by the U-boat that day to stop another sailing ship.

On 16 August 1918, U-117 resumed her mining operations, this time off Cape Hatteras, North Carolina, but the approach of the 6,978-ton British steamer Mirlo interrupted her labors. Approaching the target submerged, U-117 fired a single torpedo that sent the merchantman to the bottom. Following that attack, the submarine again began laying mines, sowing her fourth and final field. At that point, a severe shortage of fuel forced the U-boat to head for Germany.

Return journey[edit]

The return voyage proved to be both more eventful and more successful than the outward-bound cruise. On 17 August 1918, she stopped a Norwegian sailing ship, the 2,846-ton Nordhav, out of Buenos Aires, Argentina, bound for New York laden with linseed. U-117 sailors placed bombs on board the cargo carrier that sank the prize. Three days later, the U-boat engaged in an unsuccessful surface gun duel with an unidentified, strongly armed steamer. On the 26th, she stopped the 162-ton Rush and sank that American trawler with bombs placed on board. The next day, U-117 caught sight of the Norwegian freighter Bergsdalen, steaming in ballast from La Pallice, France, to Baltimore, Maryland, and sank her quarry with a single torpedo. Three days later, on 30 August, she encountered her final two victims, when she stopped the 136-ton British fishing trawlers Elsie Porter and Potentate and sank both with explosive charges.

After an unsuccessful attempt at a torpedo attack on a lone British steamer, War Ranee, on 5 September 1918, U-117 concentrated on making the final run-in toward the Skagerrak and safety. Her critical fuel shortage forced the submarine to make wireless contact with U-140 on 8 September to set up a fuel replenishment rendezvous. The two U-boats met on the 12th and 13th near the Faroe Islands, and U-117 took on about 6,000 gallons of diesel oil before continuing on toward Kiel. The submarine pulled into her destination rather ignominiously on 22 September, having had to call upon a patrolling torpedo boat to tow her the last leg of her journey.

For the rest of the war, U-117 remained inactive. On 23 October 1918, she was reassigned to the U-Flotille, Hochseeflotte (1st Submarine Flotilla, High Seas Fleet); but remained in a shipyard for the duration.

Turned over to US Navy[edit]

U-117, partially dismantled, at the Philadelphia Navy Yard, 1920

The armistice of 11 November 1918 ended hostilities, and required Germany to turn over her submarines to the Allies. U-117 surrendered at Harwich, England, ten days later. Over the ensuing weeks, the United States Navy expressed an interest in acquiring several former German submarines to serve as exhibits during a Victory Bond campaign. U-117 became one of the six boats set aside for that purpose. In March 1919, her American crew took over the submarine and placed her in special commission, Lt. Comdr. Aquilla G. Dibrell in command.

After a hectic time preparing for sea, U-117 stood down the English Channel from Harwich on 3 April in company with the submarine tender USS Bushnell (AS-2), UB-88, UB-148, and UC-97. This unlikely American task organization, dubbed the Ex-German Submarine Expeditionary Force, called at the Azores and at Bermuda before reaching New York City on 27 April 1919 where the submarines were soon opened to the public. Tourists, photographers, reporters, Navy Department technicians, and civilian submarine manufacturers all flocked in to see the six war trophies. Then orders came for her to begin a series of port visits to sell Victory Bonds. U-117 drew one of the east coast itineraries during the course of which she stopped at Washington, D.C., and spent a significant period of time at the Navy Yard located there. At the conclusion of the bond drive late that summer, the U-boat was laid up at the Philadelphia Navy Yard along with U-140 and UB-148. There, she remained — partially dismantled — until taken out to sea in June 1921 to serve as a target for aerial bombing tests conducted by the Navy and Army.


U-117 as a target ship

On 21 June 1921, three Navy Felixstowe F5L flying boats flying at an altitude of 1,200 feet bombed and sank U-117 at anchor in smooth water 50 nautical miles (93 km; 58 mi) East of Cape Charles Light Vessel, with twelve 163 pound bombs, each loaded with 117 pounds of TNT.

The bombs were dropped in two salvos, one of three bombs and one of nine bombs. Both salvos straddled and fell close to the target, all within 150 feet (46 m) of it, all bombs functioned as designed. The submarine sank within seven minutes after the second salvo. The Board of Observers did not inspect her. The submarine was an easy target, being at anchor with no one on board.

Summary of raiding history[edit]

Date Name Nationality Tonnage[Note 1] Fate[2]
10 August 1918 Aleda May  United States 31 Sunk
10 August 1918 Cruiser  United States 28 Sunk
10 August 1918 Earl & Nettie  United States 24 Sunk
10 August 1918 Katie L. Palmer  United States 31 Sunk
10 August 1918 Mary E. Sennett  United States 26 Sunk
10 August 1918 Progress  United States 34 Sunk
10 August 1918 Reliance  United States 19 Sunk
10 August 1918 William H. Starbuck  United States 53 Sunk
12 August 1918 Sommerstad  Norway 3,875 Sunk
13 August 1918 Frederic R. Kellogg  United States 7,127 Damaged
14 August 1918 Dorothy B. Barrett  United States 2,088 Sunk
15 August 1918 Madrugada  United States 1,613 Sunk
16 August 1918 Mirlo  United Kingdom 6,978 Sunk
17 August 1918 Nordhav  Norway 2,846 Sunk
20 August 1918 Ansaldo III  Kingdom of Italy 5,310 Damaged
24 August 1918 Bianca  United Kingdom 408 Damaged
26 August 1918 Rush  United States 145 Sunk
27 August 1918 Bergsdalen  Norway 2,555 Sunk
30 August 1918 Elsie Porter  United Kingdom 136 Sunk
30 August 1918 Potentate  United Kingdom 136 Sunk
29 September 1918 USS Minnesota  United States Navy 18,000 Damaged
4 October 1918 San Saba  United States 2,458 Sunk
27 October 1918 Chaparra  Cuba 1,510 Sunk
9 November 1918 Saetia  United States 2,873 Sunk



  1. ^ Merchant ship tonnages are in gross register tons. Military vessels are listed by tons displacement.


  1. ^ Gröner 1991, p. 15.
  2. ^ Helgason, Guðmundur. "Ships hit by U 117". German and Austrian U-boats of World War I - Kaiserliche Marine - Retrieved 30 April 2016. 


External links[edit]

  • Photo gallery of USS U-117 at NavSource Naval History
  • Helgason, Guðmundur. "WWI U-boats: U 117". German and Austrian U-boats of World War I - Kaiserliche Marine - Retrieved 30 April 2016.