The article examines key episodes of political struggle in the Decembrist movement both inside and between the Northern and Southern societies in 1823-1825. The course and results of the Petersburg meetings of 1824 are analyzed on the basis of “Notes” of S.P. Trubetskoy from the collection of I.A. Shlyapkin. It is shown that the meetings not only did not contribute to the consolidation of secret societies, but rather became the culmination of the pressure of P.I. Pestel to the northerners. All his initiatives were rejected. A new interpretation of the development of the Southern Society in 1825 is given. Interaction of S.P. Trubetskoy with the leaders of the Vasilkovsky society contributed to the isolation of P.I. Pestel. During this period, the views of S.P. Trubetskoy undergo changes, and he begins to support the idea of a peripheral insurrection. Another important collision is the relationship of S.P. Trubetskoy and K.F. Ryleeva. The study of this plot leads to the conclusion that S.P. Trubetskoy was disappointed by the changes that had taken place. K.F. Ryleev evoked his antipathy and could not be perceived as an ally in the implementation of political plans. But the situation changed as a result the death of Alexander I and the beginning of the interregnum. The presented analysis leads to the conclusion that the reason of the defeat of the Decembrist uprisings should be sought not in subjective factors, but in the character of the ideological split that existed in a secret society.