View source for SM U-117

{{Short description|German Type UE II submarine}}
{{Use dmy dates|date=December 2021}}
{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=SM U 117 Hafen.jpg
|Ship caption=SM ''U-117'' at [[Cape Charles (headland)|Cape Charles]]
}}
{{Infobox ship career
|Hide header=
|Ship country=[[German Empire]]
|Ship flag={{Shipboxflag|German Empire|naval}}
|Ship name= ''U-117''
|Ship ordered=
|Ship builder=[[AG Vulcan Stettin]]
|Ship yard number=91
|Ship laid down=1917
|Ship launched=10 December 1917
|Ship commissioned=28 March 1918
|Ship decommissioned=
|Ship homeport=[[Kiel]]
|Ship motto=
|Ship nickname=
|Ship honors=
|Ship fate=*Surrendered, 21 November 1918
* Taken over by the US Navy, 1919
|Ship notes=
}}
{{Infobox ship career
|Hide header=title
|Ship country=United States
|Ship flag={{USN flag|1919}}
|Ship name=''U-117''
|Ship namesake=
|Ship ordered=
|Ship builder=
|Ship laid down=
|Ship launched=
|Ship acquired=March 1919
|Ship commissioned=
|Ship homeport=
|Ship motto=
|Ship nickname=
|Ship honors=
|Ship fate=Sunk as a target, 22 June 1921
|Ship notes=
}}
{{Infobox ship characteristics
|Hide header=
|Header caption={{sfn|Gröner|1991|p=15}}
|Ship class=[[Type UE II submarine]]
|Ship type=Coastal minelaying submarine
|Ship displacement=*{{convert|1164|t|LT|0|lk=on|abbr=on}} surfaced
* {{convert|1512|t|LT|0|abbr=on}} submerged
|Ship length={{convert|81.52|m|ftin|abbr=on}} ([[o/a]])
|Ship beam={{convert|7.42|m|ftin|abbr=on}}
|Ship height={{convert|10.16|m|ftin|abbr=on}}
|Ship draught={{convert|4.22|m|ftin|abbr=on}}
|Ship propulsion=2 shafts, 2 × {{convert|1.61|m|ftin|abbr=on}} [[propeller]]s
|Ship power=*2 × [[diesel engine]]s, {{convert|2400|PS|kW shp|0|abbr=on}}
* 2 × [[Motor-generator|electric motors]], {{convert|1200|PS|kW shp|0|abbr=on}}
|Ship speed=*{{convert|14.7|kn}} surfaced
* {{convert|7|kn}} submerged
|Ship range=*{{convert|13900|nmi|abbr=on}} at {{convert|8|kn}} surfaced
* {{convert|35|nmi|abbr=on}} at {{convert|4.5|kn}} submerged
|Ship test depth={{convert|75|m|ft|abbr=on}}
|Ship complement=4 officers, 36 enlisted
|Ship sensors=
|Ship EW=
|Ship armament=*4 × {{convert|50|cm|in|1|abbr=on}} bow [[torpedo tube]]s
* 14 [[torpedoe]]s
* 2 × {{convert|100|cm|in|abbr=on}} stern mine chutes 
* 42 mines
* 1 × [[15 cm SK L/45|{{convert|15|cm|in|sp=us|abbr=on}} SK L/45]] [[deck gun]]
* 494 rounds
* 1 × [[8.8&nbsp;cm SK L/30 naval gun|{{convert|8.8|cm|in|sp=us|abbr=on}} SK L/30]] [[deck gun]]
* 310 rounds
|Ship notes=
}}
{{Infobox service record
|is_ship=yes
|label=
|partof=
|codes=
|commanders=* ''[[Kptlt.]]'' Otto Dröscher
* 28 March – 11 November 1918
|operations=1 patrol
|victories=*20 merchant ships sunk <br>({{GRT|27,459}})
* 3 merchant ships damaged <br>({{GRT|12,845}})
* 1 warship damaged <br>(18,000 tons)
}}
|}
'''SM ''U-117''''' was a [[Type UE II submarine|Type UE II]] long-range minelayer [[submarine]] of the [[Imperial German Navy]]. She was [[Keel laying|laid down]] in 1917, at [[Hamburg]], Germany, by [[AG Vulcan Stettin|Aktiengesellschaft Vulcan]] and [[Ceremonial ship launching|launched]] on 10 December 1917. She was [[Ship commissioning|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==

===Operations off North America===
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 eight of the vessels with explosives and gunfire. On 12 August, she sighted the ballast-laden steamer ''Sommerstadt'' and, after observing that the [[Norway|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 {{GRT|7127|disp=long}} American tanker ''Frederic R. Kellogg'', bound from [[Tampico]], Mexico, to [[Boston]], Massachusetts, with 7,500 barrels of crude oil. The action occurred only {{cvt|12|mi}} north of [[Barnegat Light, New Jersey]]; however, ''Frederic R. 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 and the [[Cuba]]n cargo ship ''Chaparra'' struck another mine and sank on 27 October. On 14 August, ''U-117'' took a break from mining operations to resume cruiser warfare when she encountered the American [[schooner]] ''Dorothy B. Barrett''. 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]] {{USS|SC-71||2}} 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 Light]]. That field later claimed two victims, one damaged and the other sunk. On 29 September 1918, {{USS|Minnesota|BB-22|2}} struck one of those mines and suffered extensive damage. The [[Naval Overseas Transportation Service]] cargo ship {{USS|Saetia|ID-2317|2}} 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 Quarter Shoals Lightship]], halted an American sailing vessel, the {{GRT|1613}} ''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 {{GRT|6978}} [[United Kingdom|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===
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 {{GRT|2846}} ''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 26 August, she stopped the {{GRT|145}} ''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 {{GRT|136}} 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 12 and 13 September, near the [[Faroe Islands]], and ''U-117'' took on about {{cvt|6000|gal}} of diesel oil before continuing on toward Kiel. On 20 September, ''U-117''<nowiki/>'s fuel bunkers again ran dry in the [[Kattegat]]. Two torpedo boats were dispatched to tow the powerless U-boat only to have one of the tow lines break. After transferring another 660 US gal (2,500 L) from one of the torpedo boats to ''U-117'', the submarine continued on its way, pulling alongside the pre-Dreadnought [[SMS Hannover|SMS ''Hannover'']] in the Danish Straits on the 21st where more fuel was transferred to the U-boat. ''U-117'' eventually reached base on her own power on 22 September.<ref>{{cite book |last=Etzold |first=Dominic |url=https://search.worldcat.org/title/1419490985 |title=Reaping the Whirlwind: The U-boat War off North America During World War I |date=2023 |publisher=Schiffer Military History |isbn=978-0-7643-6704-5 |publication-place=Atglen, PA |pages=272}}</ref>

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===
[[File:SM U 117 inside.jpg|thumb|''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, [[Lieutenant Commander (United States)|Lieutenant Commander]] 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|Sumner|AGS-5|2}}, and [[SM UB-88|''UB-88'']], [[SM UB-148|''UB-148'']], and {{SMU|UC-97||2}}. This unlikely American task organization, dubbed the Ex-German Submarine Expeditionary Force, called at the [[Azores]] and [[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 [[Washington Navy Yard]] 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.

===Sinking===
[[File:SM U 117 Bombing.jpg|thumb|300px|''U-117'' as a target ship]]
On 21 June 1921, three Navy [[Felixstowe F5L]] flying boats flying at an altitude of {{cvt|1200|ft}} bombed and sank ''U-117'' at anchor in smooth water {{convert|50|nmi}} East of [[Cape Charles (headland)|Cape Charles]] Light Vessel, with twelve {{cvt|163|lbs}} bombs, each loaded with {{cvt|117|lbs}} of [[Trinitrotoluol|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 {{cvt|150|ft}} 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.

==Summary of raiding history==
{| class="wikitable sortable"
|-
! width="140px"|Date
! width="140px"|Name
! width="160px"|Nationality
! width="25px" |Tonnage<ref group=Note name=tonnage>Merchant ship tonnages are in [[gross register tons]]. Military vessels are listed by tons [[displacement (ship)|displacement]].</ref>
! width="160px"|Fate<ref>{{cite Uboat.net
|id=u117
|name=U 117
|type=1boat
|accessdate = 30 April 2016
}}</ref>
|-
|align="right"|10 August 1918
|align="left" |[[List of shipwrecks in August 1918#10 August|''Aleda May'']]
|align="left" |{{flag|United States|1912}}
|align="right"|31
|align="left" |Sunk
|-
|align="right"|10 August 1918
|align="left" |[[List of shipwrecks in August 1918#10 August|''Cruiser'']]
|align="left" |{{flag|United States|1912}}
|align="right"|28
|align="left" |Sunk
|-
|align="right"|10 August 1918
|align="left" |[[List of shipwrecks in August 1918#10 August|''Earl & Nettie'']]
|align="left" |{{flag|United States|1912}}
|align="right"|24
|align="left" |Sunk
|-
|align="right"|10 August 1918
|align="left" |[[List of shipwrecks in August 1918#10 August|''Katie L. Palmer'']]
|align="left" |{{flag|United States|1912}}
|align="right"|31
|align="left" |Sunk
|-
|align="right"|10 August 1918
|align="left" |[[List of shipwrecks in August 1918#10 August|''Mary E. Sennett'']]
|align="left" |{{flag|United States|1912}}
|align="right"|26
|align="left" |Sunk
|-
|align="right"|10 August 1918
|align="left" |[[List of shipwrecks in August 1918#10 August|''Progress'']]
|align="left" |{{flag|United States|1912}}
|align="right"|34
|align="left" |Sunk
|-
|align="right"|10 August 1918
|align="left" |[[List of shipwrecks in August 1918#10 August|''Reliance'']]
|align="left" |{{flag|United States|1912}}
|align="right"|19
|align="left" |Sunk
|-
|align="right"|10 August 1918
|align="left" |[[List of shipwrecks in August 1918#10 August|''William H. Starbuck'']]
|align="left" |{{flag|United States|1912}}
|align="right"|53
|align="left" |Sunk
|-
|align="right"|12 August 1918
|align="left" |[[List of shipwrecks in August 1918#12 August|''Sommerstad'']]
|align="left" |{{flag|Norway}}
|align="right"|3,875
|align="left" |Sunk
|-
|align="right"|13 August 1918
|align="left" |[[List of shipwrecks in August 1918#13 August|''Frederic R. Kellogg'']]
|align="left" |{{flag|United States|1912}}
|align="right"|7,127
|align="left" |Damaged
|-
|align="right"|14 August 1918
|align="left" |[[List of shipwrecks in August 1918#14 August|''Dorothy B. Barrett'']]
|align="left" |{{flag|United States|1912}}
|align="right"|2,088
|align="left" |Sunk
|-
|align="right"|15 August 1918
|align="left" |[[List of shipwrecks in August 1918#15 August|''Madrugada'']]
|align="left" |{{flag|United States|1912}}
|align="right"|1,613
|align="left" |Sunk
|-
|align="right"|16 August 1918
|align="left" |[[List of shipwrecks in August 1918#16 August|''Mirlo'']]
|align="left" |{{flag|United Kingdom|civil}}
|align="right"|6,978
|align="left" |Sunk
|-
|align="right"|17 August 1918
|align="left" |[[List of shipwrecks in August 1918#17 August|''Nordhav'']]
|align="left" |{{flag|Norway}}
|align="right"|2,846
|align="left" |Sunk
|-
|align="right"|20 August 1918
|align="left" |''Ansaldo III''
|align="left" |{{flag|Kingdom of Italy}}
|align="right"|5,310
|align="left" |Damaged
|-
|align="right"|24 August 1918
|align="left" |''Bianca''
|align="left" |{{flag|United Kingdom|civil}}
|align="right"|408
|align="left" |Damaged
|-
|align="right"|26 August 1918
|align="left" |[[List of shipwrecks in August 1918#26 August|''Rush'']]
|align="left" |{{flag|United States|1912}}
|align="right"|145
|align="left" |Sunk
|-
|align="right"|27 August 1918
|align="left" |[[List of shipwrecks in August 1918#27 August|''Bergsdalen'']]
|align="left" |{{flag|Norway}}
|align="right"|2,555
|align="left" |Sunk
|-
|align="right"|30 August 1918
|align="left" |[[List of shipwrecks in August 1918#30 August|''Elsie Porter'']]
|align="left" |{{flag|United Kingdom|civil}}
|align="right"|136
|align="left" |Sunk
|-
|align="right"|30 August 1918
|align="left" |[[List of shipwrecks in August 1918#30 August|''Potentate'']]
|align="left" |{{flag|United Kingdom|civil}}
|align="right"|136
|align="left" |Sunk
|-
|align="right"|29 September 1918
|align="left" |{{USS|Minnesota|BB-22|6}}
|align="left" |{{navy|United States|1912}}
|align="right"|18,000
|align="left" |Damaged
|-
|align="right"|4 October 1918
|align="left" |[[List of shipwrecks in October 1918#4 October|''San Saba'']]
|align="left" |{{flag|United States|1912}}
|align="right"|2,458
|align="left" |Sunk
|-
|align="right"|27 October 1918
|align="left" |[[List of shipwrecks in October 1918#27 October|''Chaparra'']]
|align="left" |{{flag|Cuba}}
|align="right"|1,510
|align="left" |Sunk
|-
|align="right"|9 November 1918
|align="left" |[[List of shipwrecks in November 1918#9 November|''Saetia'']]
|align="left" |{{flag|United States|1912}}
|align="right"|2,873
|align="left" |Sunk
|}

==References==

===Notes===
{{Reflist|group=Note}}

===Citations===
{{Reflist}}

==Bibliography==
* Etzold, Dominic (2023). ''Reaping the Whirlwind: The U-Boat War off North America During WWI.'' Atglen: Schiffer Military History. {{ISBN|978-0-7643-6704-5}}
* {{cite book
|last1=Gröner
|first1=Erich
|last2=Jung
|first2=Dieter
|last3=Maass
|first3=Martin
|translator-last1=Thomas
|translator-first1=Keith
|translator-last2=Magowan
|translator-first2=Rachel
|year=1991
|title=U-boats and Mine Warfare Vessels
|volume=2
|series=German Warships 1815–1945
|location=London
|publisher=Conway Maritime Press
|isbn=0-85177-593-4
|ref=CITEREFGröner1991
}}
* {{DANFS|http://www.history.navy.mil/danfs/u1/u-117.htm|publisher=[[Dictionary of American Naval Fighting Ships]]|title=U-117}}
* [[Media:New York Times the sinking of SS Sommerstadt.pdf|New York Times Report of ''U-117'' sinking the SS ''Sommerstadt'']]

==External links==
{{Commons category|SM U 117 (submarine, 1917)|SM U 117}}
* {{navsource|08/08433|USS U-117}}
* {{cite Uboat.net
 |id=117
 |name=U 117
|type=1sub
|accessdate = 30 April 2016
}}

{{German Type UE II submarines}}
{{1921 shipwrecks}}

{{DEFAULTSORT:U0117}}
[[Category:German Type UE II submarines]]
[[Category:U-boats commissioned in 1918]]
[[Category:World War I submarines of Germany]]
[[Category:U-boats sunk in 1921]]
[[Category:1917 ships]]
[[Category:U-boats sunk by US aircraft]]
[[Category:Ships sunk as targets]]
[[Category:Maritime incidents in 1921]]