The first displays of mutinous spirit among the men of the fleet were not so much due to revolutionary and radical Socialist propaganda as to a spontaneous internal dissatisfaction with the conditions of the service itself. No continuously extensive use of the submarines had been made up to the middle of the winter of 1916. There had been spurts of activity with this weapon, but no sustained effort. By March, 1916, however, many U-boats were being sent out. At first they were manned by volunteers, and there had been a surplus of volunteers, for the men of the submarine crews received special food, more pay, liberal furloughs and the Iron Cross after the third trip. Within a year, however, conditions changed decidedly. The percentage of U-boats lost is not yet known, but the men of the fleet reckoned that a submarine rarely survived its tenth trip. The Admiralty naturally published no accounts of boats that failed to come back, and this added a new terror to this branch of the service. Volunteers were no longer to be had. The result was that drafts were resorted to, at the first from the men of the High Seas fleet, and later from the land forces. Such a draft came to be considered as equivalent to a death-sentence.[16] Disaffection increased in the fleet. The Independent Socialists were prompt to discover and take advantage of these conditions. The sailors were plied with propaganda, oral and written. The character of this propaganda was not generally known until October 9, 1917, when the Minister of Marine, Admiral von Capelle, speaking in the Reichstag, informed the astonished nation that a serious mutiny had occurred in the fleet two months earlier, and that it had been necessary to execute some of the ringleaders and imprison a number of others. [16] The heavy losses among army aviators had brought about a similar state of affairs at this time in the army. Volunteers for the fighting planes ceased offering themselves, and a resort to forced service became necessary. Von Capelle's disclosures came as answer to an interpellation by the Independent Socialist deputies regarding pan-German propaganda at the front and the prohibition of the circulation of twenty-three Socialist newspapers among the men of the ships. The Independent Wilhelm Dittmann made a long speech supporting the interpellation, and voiced a bitter complaint over the fact that pan-German agitation was permitted at the front and among the fleet, while the Independent Socialist propaganda was forbidden. Dr. Michaelis, the Imperial Chancellor, made a brief response, in which he announced that Admiral von Capelle would answer the Independents. "I will merely say one thing," he said, "and that is that Deputy Dittmann is the last man in the world who has a right to talk about agitation in the army and navy."