The significance of father Gapon's march and bloody Sunday is that it led to the events of the Revolution of 1905.
Father Gapon's march and Bloody Sunday were significant events in the lead-up to the Russian Revolution. Father Gapon led a peaceful protest march to present a petition to Tsar Nicholas II, but it ended in a massacre when the Tsar's troops fired on the crowd. This event fueled widespread discontent and served as a catalyst for revolution, as it exposed the brutality of the Tsarist regime and energized revolutionary groups in their fight against autocracy.
Astonishing is the term that best describes the significance of Father Gapons March and bloody.
It led to the events of the Revolution of 1905. Hope this helps!