[Note 1] UB-17 spent her entire career in the Flanders Flotilla and sank 13 ships, most of them British fishing vessels.

[9][Note 3] On 10 May, UB-17 joined the Flanders Flotilla (German: U-boote des Marinekorps U-Flotille Flandern),[1] which had been organized on 29 March.

During this campaign, enemy vessels in the German-defined war zone (German: Kriegsgebiet), which encompassed all waters around the United Kingdom, were to be sunk.

Despite the loss of six men, Batoum's crew was able to beach the ship, listed as 4,054 gross register tons (GRT).

[11][Note 4] Early the next month, on 6 August, Wenninger and UB-17 sank four British fishing vessels while patrolling in the Yarmouth–Lowestoft area.

[12][13] All four of the sunken ships were smacks—sailing vessels traditionally rigged with red ochre sails[14]—which were stopped, boarded by crewmen from UB-17, and sunk with explosives.

Holtzendorff's directive ordered all U-boats out of the English Channel and the South-Western Approaches and required that all submarine activity in the North Sea be conducted strictly along prize regulations.

[17] Enemy naval targets were not subject to the prize regulations, so on 23 September, Wenninger torpedoed and sank the Saint Pierre I, a trawler of the French Navy off the Dyck lightship.

[12][20] The next day, UB-17's war journal (German: Kriegstagebücher or KTB) records the torpedoing of the 957 GRT British steamer Franz Fischer off the Kentish Knock.

[26] UB-17 sank no ships during this offensive,[12] which was called off near the end of April by Admiral Reinhardt Scheer, the commander-in-chief of the High Seas Fleet.

[28] In support of the operation, UB-17 and five other Flanders boats set out at midnight 30/31 May to form a line 18 nautical miles (33 km; 21 mi) east of Lowestoft.

[29][Note 5] This group was to intercept and attack the British light forces from Harwich, should they sortie north to join the battle.

The 462 GRT steamer was en route to London from Rotterdam with a cargo of piece goods when she was sunk 19 nautical miles (35 km; 22 mi) from the Mass Lightship.

While Meier remained in command of UB-17, Kaiser Wilhelm II personally approved a resumption of unrestricted submarine warfare to begin on 1 February 1917 to help force the British to make peace.

[36] Although the new rules of engagement specified that no ship was to be left afloat,[37] UB-17 did not contribute to the effort until December 1917, when she captured and sank a single fishing smack off Aldeburgh under the direction of Oblt.

[41] Messimer also discounts an account that attributes UB-17's sinking to British destroyer Onslow on 25 February south of Portland by pointing out that UB-17 was in port in Zeebrugge on that date.

[41] A German postwar study also rejected a British claim that destroyers HMS Thruster, Retriever, and Sturgeon sank UB-17 at 21:25 on 11 March at position 57°7′N 2°43′E / 57.117°N 2.717°E / 57.117; 2.717 because UB-17 didn't depart Zeebrugge until 30 minutes after the attack took place.

[1] In July 2013, archaeologists found the remains of 44 submarines, including UB-17, off the United Kingdom's southern and east coasts, near the county of Suffolk.

Der Spiegel reported divers located 41 German U-boats, and three of English submarines, found at depths of up to 50 feet, off England's southern and eastern coasts.