The development of pre-war Indonesian nationalism may be divided into four periods. The first period witnessed the shy initial attempts to achieve improvements in the cultural, economic, political and religious fields, stimulated more or less by the then prevalent Ethical Policy of the Dutch administration. During the late tens and the early twenties the political scene was dominated by the Sarekat Islam and the Partai Komunis Indonesia, at first collaborating, later competing with each other, but, whatever their mutual relations, both responsible for an amount of vociferous agitation and political vivacity which highly upset Dutch official and private circles. The abortive communist revolts of 1926–7 led to a harsh repression of everything communist, while the Sarekat Islam was losing its hold over the masses with which it had lost contact already after it had thrown out the leftists. At this stage real nationalism began to fill the vacuum caused by the disappearance of the P.K.I, and the powerlessness of the S.I. There is no doubt that the previous agitation had been motivated by genuine nationalist feelings, but these had either been subordinated to or run parallel with more internationally inclined movements such as Islamic reformism and Marxist socialism. After 1926, however, nationalism – and professedly Indonesian nationalism for that matter – was made the basic principle of political action. This became clear when the oldest party, the very cautious, in its origins very aristocratic and hardly more than Central Javanese Boedi Oetomo decided to include Indonesian nationalism into its programme. The new trend received its most clear expression, of course, in Soekarno's Partai Nasional Indonesia, which advocated a Free Indonesia, to be achieved by non-cooperation with the Dutch administration and the broadest possible co-operation with other political parties.