During Alexander III's reign, the monarchy's opponents quickly disappeared underground. A group of students had been planning to assassinate Alexander III on the sixth anniversary of his father's death at the Peter and Paul Cathedral in St. Petersburg. The plotters had stuffed hollowed-out books with dynamite, which they intended to throw at the Tsar when he arrived at the cathedral. However, the Russian secret police uncovered the plot before it could be carried out. Five students were hanged in 1887; amongst them was Aleksandr Ulyanov, older brother of Vladimir Lenin.