Complex sentence: At the beginning of February 1918, Bogdanov denied that the Bolsheviks had constituted a conspiracy, but rather explained that an explosive situation had arisen through the prolongation of the war.
Split into simpler sentences: At the beginning of February 1918, Bogdanov denied that the Bolsheviks had constituted a conspiracy. Rather, he explained that an explosive situation had arisen through the prolongation of the war.