The Ottoman Period
From the time the modern Jewish community in Palestine (the new yishuv) became an entity following the first and second aliyot (waves of immigration) - from 1870 until the outbreak of World War I in 1914 - every Jewish town, neighborhood, moshava (village), farm, moshav and kvutza (cooperative and collective settlements, respectively), faced the necessity of protecting itself. At the time, protection was necessary mainly against local Arab thieves, individuals and organized gangs.
Jewish security organizations evolved in several phases. At first, Jewish settlements designated at least one person to be responsible for the security of the built-up area and, when necessary, the fields. This guard, armed with a personal weapon (a rifle and, in most cases, also a handgun) operated by day and by night, on horseback or on foot. As time passed, these guards hired Arabs for guard duty, especially at night. The method proved inefficient because soon the Arab guards began to collaborate with the thieves and bandits. As a result, in a few settlements (Zikhron Ya'akov is one example) young Jewish settlers organized small groups for guard duty on a voluntary basis, having learned the art of guarding and securing their settlements from the very few professionals.
In these circumstances, with guard duties in most settlements carried out by Arabs, and in some villages by young Jewish "irregular" volunteers - the Bar Giora organization was founded in 1907 in the home of Yitzhak Ben-Zvi, who later became Israel's second president, in Neve Tzedek, near Jaffa. Bar Giora established the first communes of Jewish guards at Sejera. From within these communes of workers and guards Hashomer was founded in 1909, defining itself as a countrywide organization that would assume responsibility for the security of as many Jewish settlements as possible. Hashomer's condition, before undertaking to guard and secure any settlement, was that only Jewish laborers be employed in it. Hashomer was thus able to regard these laborers as a reserve for guard duty and quickly organized its operations in a three-tiered hierarchy: a small core of founders (veterans of Bar Giora); a larger circle of active guards, members of Hashomer; and the Jewish laborers, who termed themselves a "labor legion", as reserves.
In 1913, the Hashomer leadership established relations with the institutions of the Zionist Organization in Europe, but this connection was disrupted in August 1914 when World War I broke out. Hashomer continued its security assignments in Palestine as before, taking pains to deny the Ottoman regime any pretext to liquidate it. An additional security organization came into being at this time: the Jaffa Group, comprised of young people who provided security services for Tel Aviv and the Jewish community in Jaffa. The leading personality in Hashomer throughout its existence (1909-1920), was Yisrael Shohat; the main figure in the Jaffa Group was Eliyahu Golomb.