Final answer:
The assassination of Tsar Alexander II was the catalyst for reform during his reign, showing that the reforms implemented were not enough for many Russians.
Step-by-step explanation:
The event that was the catalyst for reform during Alexander II's reign was the assassination of the Tsar on March 13, 1881, by terrorists in the streets of St. Petersburg. The assassination of Tsar Alexander II was the catalyst for reform during his reign, showing that the reforms implemented were not enough for many Russians.
This event showed that the reforms implemented by Alexander II were not enough for many Russians, leading to radical groups calling for more revolutionary changes. The assassination of Tsar Alexander II was the catalyst for reform during his reign, showing that the reforms implemented were not enough for many Russians. The assassination of the Tsar sparked further repression and a return to harsh methods by his successor, Alexander III.