The Dove

The Dove was a name given to a large Hydrogen blast that destroyed the capital of Hyperion in District 13. The blast itself has been declared the cause of the largest loss of human life in a day in history, surpassing the 1898 Martian Invasion.

All Good Men
With Hari Seldon, the leader of the Upper High and coordinator of the League, now dead, the Upper High vote in the cut all chances of failure and destroy Hyperion. "The Dove" refers to a mega blast of the sun's radiated energy harnessed by the Upper League's ship, Orion. The blast was fired from Orion and made contact with the earth's surface. In the process of doing so, the blast demolished much of Hyperion, leaving nearly the entire city to waste and claiming many lives.

Aftermath
The result of the blast sparked much ethical debate among the galaxy.