10,000 reservists (all aged between 18 and 25) and an elite unit, the Palmach composed of 2,100 fighters and 1,000 reservists. The reservists trained three or four days a month and went back to civilian life the rest of the time. These mobile forces could rely on a garrison force, the HIM (Heil Mishmar, lit. Guard Corps), composed of people aged over 25. The Yishuv's total strength was around 35,000 with 15,000 to 18,000 fighters and a garrison force of roughly 20,000. There were also several thousand men and women who had served in the British Army in World War II who did not serve in any of the underground militias but would provide valuable military experience during the war. Walid Khalidi says the Yishuv had the additional forces of the Jewish Settlement Police, numbering some 12,000, the Gadna Youth Battalions, and the armed settlers. Few of the units had been trained by December 1947. On 5 December 1947, conscription was instituted for all men and women aged between 17 and 25 and by the end of March, 21,000 had been conscripted. On 30 March, the call-up was extended to men and single women aged between 26 and 35. Five days later, a General Mobilization order was issued for all men under 40. Irgun The Irgun, whose activities were considered by MI5 to be terrorism, was monitored by the British. By March 1948, the Yishuv had a numerical superiority, with 35,780 mobilised and deployed fighters for the Haganah, 3,000 of Stern and Irgun, and a few thousand armed settlers. Arab forces According to Benny Morris, by the end of 1947, the Palestinians already "had a healthy and demoralising respect for the Yishuv's military power" and if it came to battle, the Palestinians expected to lose. When the first violent incidents broke out in Jerusalem on the 29 November, the Arab Higher Committee, well aware of their lack of armaments, had called for a three day strike: the most militant Palestinian group in the city, consisting of 44 fighters, was furnished with 12 rifles, some handguns and a few kilograms of explosives. The effective number of Arab combatants is listed as growing to 12,000 by some historians while others calculate an eventual total Arab strength of approximately 23,500 troops, and with this being more of less or roughly equal to that of the Yishuv. However, as Israel mobilised most of its