Tunguska event

The Tunguska event was an Assassin strike against the Templars in 1908, lead by Assassin ally Nikola Tesla. Tesla used his machines at the Assassins' behest to broadcast his electricity to Tunguska, Russia. This destroyed the Piece of Eden there, and caused an enormous explosion.

Importance
The strike was a major Assassin victory in the early twentieth century, and eliminated a Piece of Eden, as well as a Templar research facility.