The goal of the committees was to prepare for a coordinated uprising. The network of committees was at its densest in the central Bulgarian regions, particularly around Sofia, Plovdiv and Stara Zagora. Revolutionary committees were also established in some parts of Macedonia, Dobruja and Strandzha and around the more peripheral urban centres Kyustendil, Vratsa and Vidin. IRO committees purchased armaments and organised detachments of volunteers. According to one study, the organisation had just over 1,000 members in the early 1870s. Most members were intellectuals and traders, though all layers of Bulgarian society were represented. Individuals obtained IRO membership in secrecy: the initiation ritual involved a formal oath of allegiance over the Gospel or a Christian cross, a gun and a knife; treason was punishable by death, and secret police monitored each member's activities. Through clandestine channels of reliable people, relations were maintained with the revolutionary diasporic community. The internal correspondence employed encryption, conventional signs, and fake personal and committee names. Although Levski himself headed the organisation, he shared administrative responsibilities with assistants such as monk-turned-revolutionary Matey Preobrazhenski, the adventurous Dimitar Obshti, and the young Angel Kanchev. Apocryphal and semi-legendary anecdotal stories surround the creation of Levski's Internal Revolutionary Organisation. Persecuted by the Ottoman authorities who offered 500 Turkish liras for his death and 1000 for his capture, Levski resorted to disguises to evade arrest during his travels. For example, he is known to have dyed his hair and to have worn a variety of national costumes. In the autumn of 1871, Levski and Angel Kanchev published the Instruction of the Workers for the Liberation of the Bulgarian People, a BRCC draft statute containing ideological, organisational and penal sections. It was sent out to the local committees and to the diasporic community for discussion. The political and organisational experience that Levski amassed is evident in his correspondence dating from 1871 to 1872; at the time, his views on the revolution had clearly matured. As IRO expanded, it coordinated its activities more with the Bucharest-based BRCC. On Levski's initiative, a general assembly was called between 29 April and 4 May 1872. At the assembly, the delegates approved a programme and a statute, elected Lyuben Karavelov as the organisation's leader and authorised Levski as the BRCC executive body's only legitimate representative in the Bulgarian lands. After attending the assembly, Levski returned to Bulgaria and reorganised IRO's internal structure in accordance with BRCC's recommendations.