On January 26, 1913, the first party congress was held in Surabaya which gathered tens of thousands of participants. The congress was marked by the rise of Oemar Said Tjokroaminoto as the new leader of SI. Under the charismatic leadership of Tjokroaminoto, who was hailed as a messianic figure or Ratu Adil, the organization rapidly expanded the network throughout Java and later spread to the outer islands. SI also began publishing periodicals in the Surabaya, Semarang, Bandung, and Batavia branches. Membership of SI rapidly grew from 4,500 in April 1912 to 150,000 in April 1913 and eventually 350,000 in 1916. Other report estimated the membership to be 800,000. SI itself claimed 2 million members in 1919. The rapid increase of SI membership led to the expansion of the supporter base to a wide array of social classes. Although SI leaders generally espoused Modernist Islam, it became heterogeneous in terms of demographics and ideology of its grassroots members. While the initial supporter base was a petty bourgeoisie of religiously devout aliran (societal stream) of santri, the expansion had led to the inclusion of peasantry of abangan whose Islamic faith was mixed with mysticism and pre-Islamic animist beliefs, as well as members of priyayi nobility class who had secular outlooks. The leadership of the organization gradually moved from small-scale merchants of the SDI era to the intelligentsia of priyayi origin with Dutch-language education. During this time, the central leadership of SI strived to maintain harmony between the Dutch colonial administration. SI proclaimed to uplift the welfare of the indigenous population under Dutch rule and demanded self-governance through constitutional means. Tjokroaminoto declared the rejection of anti-government activity during the 1913 congress, during which he insisted on "loyalty" and "satisfaction" toward the Dutch government and denied the allegation that the organization serves as a political party. As a response, the colonial government did not attempt to suppress SI in the beginning. In November 1912, SI requested the colonial administration to recognize them as a legal entity. The government individually authorized the regional branches of SI on June 30, 1913, and eventually gave an official permit to the SI headquarters in 1916. Despite the non-confrontational stance of the SI leadership, the spread of SI in the villages had led to the outburst of violence, where peasants and villagers perceived SI as a means of self-defence and expression of group solidarity against the oppressive power structure