"The Weapon Too Dreadful To Use" was published in the May 1939 issue of Amazing Stories. It was reprinted in the August 1965 issue of Amazing and the 1972 collection The Early Asimov.
"The Weapon Too Dreadful to Use" was the eleventh story written by Asimov, but the second to be published.
The people of Earth have colonised Venus, despite the intelligent species native to the planet, who are treated as inferiors with no rights.
One of the Venusians shows his Earthman friend the ruins of an ancient city, where they discover details of an ancient weapon, apparently abandoned millennia before as being too dreadful to actually use, but, as the domination by the colonists increases, elements of the Venusian resistance obtain the weapon and use it on the colonial cities and their population. The weapon works by disconnecting the brain from the mind, and within a short time, the Venusians take back control of their planet from the defenseless colonists.
Earth surrenders and signs a peace treaty with Venus. The Venusians then destroy the weapon.