Complex sentence: The date for his first appearance was Sunday, March 1 1881, two hours after the review his uncle who has been present there on the insistence of Alexandra Iosifovna, was assassinated.
Split into simpler sentences: The date for his first appearance was Sunday, March 1,1881. Two hours after the review, his uncle, who had been present there at the insistence of Alexandra Iosifovna, was assassinated.