"In principle, the SS was to accept no new members after 1933, except from selected graduates of the Hitler Youth. However, the creation of the Waffen-SS and its rapid growth caused the partial suspension of this rule. However, service in the Waffen-SS did not necessarily include membership in the SS proper. Prior to the war, suitable SS candidates were singled out while still in the Hitler Youth (HJ). Boys who had proved themselves, often under SS leadership, in the HJ patrol service were often tabbed for later SS service. If the candidate satisfied SS requirements in political reliability, racial purity, and physique, he was accepted as a candidate at the age of 18. At the annual Nazi Party Congress in September, candidates were accepted, received SS certificates, and were enrolled in the SS. Service in the Waffen-SS was officially voluntary. The Waffen-SS claimed priority over all other branches of the armed forces in the selection of recruits. Eventually, to meet the high rate of casualties and the expansion of Waffen-SS field divisions, service in the Waffen-SS became compulsory for all members of the SS, and the voluntary transfer of personnel from any other branch of the armed forces was permitted. From 1943, pressure was exerted on members of the Hitler Youth to volunteer for the Waffen-SS. Later, entire Army, Navy, and Air Force units were taken over by the Waffen-SS, given SS training, and incorporated into field units. Waffen-SS enlistment drives in Germany were nearly continuous. Waffen-SS recruitment was regionally organized and controlled."