On March 12th 1907 battleship
Iena exploded while on dry dock.
On 4 March 1907
Iéna was moved into Dry dock No. 2 in the Missiessy Basin at Toulon to undergo maintenance of her hull as well as an inspection of her leaking rudder shaft. Eight days later, beginning at 13:35 and continuing until 14:45, a series of explosions began near the aft 100-millimetre magazines which devastated the ship and the surrounding area. The explosions blew the roofs off three nearby workshops and gutted the area between the aft funnel and the aft turret. Because the ship was in a dry dock with the water pumped out, it was initially impossible to flood the magazines, which had not been unloaded before docking. The commanding officer of the battleship Patrie, which was moored nearby, fired a shell into the dry dock gates in an attempt to flood it, but the shell ricocheted without holing the gate. They were manually opened shortly afterwards by one of the ship's officers. A total of 118 crewmen and dockyard workers were killed by the explosions, as were 2 civilians in the suburb of Pont-Las who were killed by fragments.
On 17 March, the President of France, Armand Fallières, and Georges Clemenceau, who was both the President of the Council of Ministers and Minister of the Interior attended the funeral of those lost during the explosion. A national day of mourning was declared and a monument was built in the cemetery of Lagoubran. Both houses of the French Parliament, the Senate and the Chamber of Deputies, organised commissions to inquire into the cause of the explosion. The Senate appointed its commission on 20 March under the chairmanship of Ernest Monis; the Chamber of Deputies followed eight days later with Henri Michel as chair.
The origin of the first explosion was traced to a 100 mm magazine and was believed to have been caused by decomposing Poudre B, a nitrocellulose-based propellant, which tended to become unstable with age and self-ignite, though a report published in April 1907 stated a torpedo exploded in the torpedo room directly below the magazine. When burnt, it gave off yellow-coloured smoke, which matched the colour seen by eye-witnesses. To test this theory, Gaston Thomson, the Navy Minister, ordered on 31 March that a replica magazine and the adjacent black-powder magazine be built, but when the tests were conducted on 6–7 August, they were deemed inconclusive because the propellant used in the test was not of the same age as that aboard Iéna. Fallières appointed a technical commission on 6 August that included mathematician Henri Poincaré, chemist Albin Haller and the inventor of Poudre B, Paul Vieille, that failed to come to a definite conclusion. The navy's Propellant Branch (Service des Poudres et Saltpêtres) objected to the criticisms of its product, claiming that it was tested to resist 43 °C (110 °F) temperatures for 12 hours, although it never explained how that test was relevant to the long-term storage of Poudre B in magazines limited to natural ventilation, as was used by every ship in the fleet. The Monis Commission published its report on 9 July, blaming the explosion on Poudre B, and was debated on 21–26 November. The Michel Commission published its report on 7 November 1908, although its contents had been debated on 16–19 October, and was "a model of vagueness and imprecision". The reason for the explosion became a cause célèbre with accusations of gross negligence by the government such that Thomson was forced to resign on the last day of the debate.
Disposal
The multiple explosions ripped open the ship's side between Frames 74 and 84 down to the lower edge of the armour belt, and all the machinery in this area was destroyed. After it was estimated that it would take seven million francs and two years to fully repair
Iéna, which was already obsolete, the navy decided to decommission her and use her as a target ship.