The most unusual feature of his design was the prominent forecastle that was built atop the forward part of the pressure hull, while the rear was virtually awash.

It noted that she had problems with a following sea as the superstructure rapidly filled with water, but drained slowly so that she was much heavier by the bow and would tend to wallow.

[2] For surface running, the boat was powered by two Sautter & Harlé six-cylinder, 700-metric-horsepower (690 bhp; 515 kW) diesel engines, each driving a 1.72-meter (5 ft 8 in) propeller.

The boat was refitted and further repairs were made to the port-side motor, although continuing problems with her propulsion system often immobilized Mariotte into 1912.

After repeated breakdowns, Mariotte conducted her testing of the diesels from 23 October to 11 December and she was finally commissioned (armament définitif) on 5 February 1913 after a complete overhaul of her propulsion system.

[8] When World War I began in August 1914, Mariotte was transferred to the Mediterranean Squadron at Toulon where she patrolled off the coast of Provence.

After making a reconnaissance flight over the straits and having studied the reports of the British submarines that had successfully entered the Dardanelles, Lieutenant de vaisseau Auguste Farbre ordered his crew to cast off on the evening of 25 July.

Escorted by the French destroyer Poignard to the mouth of the Dardanelles, she rounded Cape Helles on the surface, but dived to avoid being spotted by a searchlight about an hour later and attempted to pass underneath a minefield near Çanakkale.

The boat became entangled in the cables and when she surfaced in an unsuccessful attempt to free herself, she was immediately engaged by a Turkish gun battery at close range.

The Turks ceased fire when he signaled his surrender and so his crew was able to destroy documents and equipment before opening the seacocks to sink the submarine.