Tesla Invented a "Directed Energy Weapon"
Hmm, I wonder what REALLY happened with this:
“ I have not thought it hazardous to predict, that wars in the future will be waged by electrical means. ”
—Nikola Tesla, 1915, 
Later in life, Tesla made some remarkable claims concerning a "teleforce" weapon The press called it a "peace ray" or death ray. In total, the components and methods included:
--An apparatus for producing manifestations of energy in free air instead of in a high vacuum as in the past. This, according to Tesla in 1934, was accomplished.
--A mechanism for generating tremendous electrical force. This, according to Tesla, was also accomplished.
--A means of intensifying and amplifying the force developed by the second mechanism.
--A new method for producing a tremendous electrical repelling force. This would be the projector, or gun, of the invention.
Tesla worked on plans for a directed-energy weapon between the early 1900s till the time of his death. In 1937, Tesla composed a treatise entitled "The Art of Projecting Concentrated Non-dispersive Energy through the Natural Media" concerning charged particle beams. Tesla published the document in an attempt to expound on the technical description of a "superweapon that would put an end to all war". This treatise of the particle beam is currently in the Nikola Tesla Museum archive in Belgrade. It described an open ended vacuum tube with a gas jet seal that allowed particles to exit, a method of charging particles to millions of volts, and a method of creating and directing nondispersive particle streams (through electrostatic repulsion).
Records of his indicate that it was based on a narrow stream of atomic clusters of liquid mercury or tungsten accelerated via high voltage (by means akin to his magnifying transformer). Tesla gave the following description concerning the particle gun's operation:“ [The nozzle would] send concentrated beams of particles through the free air, of such tremendous energy that they will bring down a fleet of 10,000 enemy airplanes at a distance of 200 miles from a defending nation's border and will cause armies to drop dead in their tracks. ”
The weapon could be used against ground based infantry or for antiaircraft purposes.
Tesla tried to interest the US War Department in the device. He also offered this invention to European countries. None of the governments purchased a contract to build the device. He was unable to act on his plans.