In mid-December, Curie's commander conceived a plan to infiltrate the Austro-Hungarian Navy's main base at Pola, but during the 20 December attempt, the vessel became ensnared in harbor defenses.

The Austro-Hungarian Navy, which had a small and largely obsolete[citation needed] U-boat fleet, immediately began salvage efforts and succeeded in raising the lightly damaged submarine in early February 1915.

[2] The Brumaire class featured twin propeller shafts driven by two French license-built MAN 6-cylinder diesel engines on the surface, or by two electric motors when submerged.

[3] On 17 December 1914, Curie, at the insistence of her French-Irish commander Gabriel O'Byrne, departed her base in the Ionian Sea under tow by the French armored cruiser Jules Michelet.

On 19 December, O'Byrne took Curie in to observe the anti-submarine net that ran across the opening in a long, defensive breakwater built to keep submarines from infiltrating the naval base.

[5][6] Believing that he had accounted for all of the defensive measures, O'Byrne took Curie to a depth of 65 feet (20 m) early on 20 December and, attempting an incursion into the harbor, heard the sounds of chains and wires dragging on the submarine's hull.

When the sounds stopped after half a minute, O'Byrne brought Curie up to periscope depth to discover that he had only penetrated the outer net.

[7] When the submarine, still trapped in the net, was forced to surface for fresh air, Curie came under fire from the Austro-Hungarian destroyer Magnet and torpedo boat Tb 63 T which quickly sank her.

[8][Note 1] At the beginning of the First World War, the Austro-Hungarian Navy's U-boat fleet consisted of six largely experimental submarines of three classes.

Beginning on 21 December, the day after Curie's sinking, salvage crews raised the submarine in stages, finally bringing her to the surface on 2 February 1915.

[13] U-14 survived a depth charge attack, but made it back to port with all of her externally mounted torpedoes crushed and both fuel tanks leaking.

[21] Heading into the Ionian Sea,[21] von Trapp and U-14 sank the French steamer Constance on 23 August 142 nautical miles (263 km; 163 mi) northeast of Malta.

The 3,627-ton turret deck ship, on her way from Malta to Port Said with coal, was sunk on the night of 27/28 August 125 nautical miles (232 km; 144 mi) from Benghazi.

[25] On 29 August, von Trapp sank the Italian steamer Milazzo 250 nautical miles (460 km; 290 mi) east of Malta.

[29] Nearby, and on the same day, von Trapp sank the 3,618-ton Good Hope, a British ship laden with iron ore for Middlesbrough.

[20] After Austria-Hungary's surrender and the end of the First World War, U-14 was returned to France and on 17 July 1919 rejoined the French Navy under her former name of Curie.

[1] ^Note 1 The French submarine Pierre Chailley, laid down in May 1917 and launched in December 1922, was named in honor of Curie's second officer, one of the three men killed in the sinking.

[1] ^Note 4 During this time, Austria-Hungary was engaged in protracted negotiations with Germany in efforts to secure purchase of German Type UB 1 boats.