The Haganah (Hebrew for "defence"), a Jewish paramilitary organisation, actively supported British efforts to suppress the uprising, which reached 10,000 Arab fighters at their peak during the summer and fall of 1938. Although the British administration did not officially recognise the Haganah, the British security forces cooperated with it by forming the Jewish Settlement Police, Jewish Supernumerary Police, and Special Night Squads. The Special Night Squads engaged in activities described by colonial administrator Sir Hugh Foot, as 'extreme and cruel' involving torture, whipping, abuse and execution of Arabs.The British authorities maintained, financed and armed the Jewish police from this point onward until the end of the Mandate, and by the end of September 1939 around 20,000 Jewish policeman, supernumeraries and settlement guards had been authorised to carry arms by the government, which also distributed weapons to outlying Jewish settlements, and allowed the Haganah to acquire arms. Independently of the British, Ta'as, the Haganah's clandestine munitions industry, developed an 81-mm mortar and manufactured mines and grenades, 17,500 of the latter being produced for use during the revolt.In June 1937, the British imposed the death penalty for unauthorised possession of weapons, ammunition, and explosives, but since many Jews had permission to carry weapons and store ammunition for defence this order was directed primarily against Palestinian Arabs and most of the 112 executed in Acre Prison were hanged for illegal possession of arms.In principle all of the joint units functioned as part of the British administration, but in practice they were under the command of the Jewish Agency and "intended to form the backbone of a Jewish military force set up under British sponsorship in preparation for the inevitable clash with the Arabs." The Agency and the Mandate authorities shared the costs of the new units equally. The administration also provided security services to Jewish commercial concerns at cost.Jewish and British officials worked together to co-ordinate manhunts and collective actions against villages and also discussed the imposition of penalties and sentences. Overall, the Jewish Agency was successful in making "the point that the Zionist movement and the British Empire were standing shoulder to shoulder against a common enemy, in a war in which they had common goals."The rebellion also inspired the Jewish Agency to expand the intelligence-gathering of its Political Department and especially of its Arab Division, with the focus changing from political to military intelligence. The Arab Division set up a network of Jewish controllers and Arab agents around the country. Some of the intelligence gathered was shared with the British administration, the exchange of information sometimes being conducted by Moshe Shertok, then head of the Jewish Agency, directly with the high commissioner himself. Shertok also advised the administration on political affairs, on one occasion convincing the high commissioner not to arrest Professor Joseph Klausner, a Revisionist Maximalist activist who had played a key role in the riots of 1929, because of the likely negative consequences.