The Submarine Command Course (SMCC), previously known as the Commanding Officers Qualifying Course (COQC), and informally known as The Perisher is a training course for naval officers preparing to take command of a submarine. Created by the Royal Navy during World War I, the course was originally intended to address the high attrition rate of submarine commanders, as the previous method of handing down knowledge from officer to officer was prevented by wartime deaths. Following World War II, the Royal Netherlands Navy became involved in the course; the Dutch later partnered with the British to run the course, and following the British conversion to a fully nuclear submarine fleet, took over responsibility for running the course for diesel-electric submarines. Officers from other nations regularly participate. The four-month course is run in four stages, the first and third involve learning ashore in simulators, while the second involves learning at sea. The fourth phase is the assessment, during which the candidates (of which the maximum is six) show their ability to command a submarine unaided during war-like conditions. The success rate for the SMCC is 60% and, on failing, candidates are prevented from serving on submarines in any capacity. Formation and history Prior to World War I, knowledge relating to command of a submarine was passed on from a boat's commander to his replacement. However high attrition rates during the war meant this training could not always be passed on, and the less experienced submarine commanders were in turn more likely to make errors resulting in their death and the loss of the boat. In 1917, the Royal Navy established the COQC for potential commanding officers. Perisher (as the Submarine Command Course is better known - owing to the fact the course used to be called the Periscope School and those officers attending being referred to as Perishers ) is a 24-week course that officers must take prior to serving as an executive officer on board a Royal Navy Submarine. It has been run twice a year since 1917, usually starting on 2 July and 14 November each year. It is widely regarded as one of the toughest command courses in the world. Following World War II, the Royal Netherlands Navy began to send officers to the course. Until 1995, the Royal Navy and Royal Netherlands Navy were jointly responsible for running the SMCC. In 1995 the Royal Netherlands Navy took over