The Brahmastra (astra is a suffix that means ‘weapon’) was a superweapon created by Brahma, part of the Hindu Trinity along with Vishnu and Shiva. It was considered the ultimate weapon that destroyed everything, and there was only one defense against it, the Brahmadananda. Another weapon, known as the Brahmashira, was even more powerful. The main adversaries in the Ramayana, Rama and Ravana are said to have each used a Brahmashira in their epic battle, at a time many years earlier than the battle at Kurukshetra. Other super-weapons are “Rama’s Arrow,” the “trishul,” and the “chakram,”—personal weapons of the gods, but apparently also used by normal humans in many fights with each other, often over who marries whom or who gets the seat of power after daddy dies— themes still common in India today.
As described in a number of the Puranas, it was considered the deadliest weapon. It was said that when the Brahmastra was discharged, there was neither a counter attack nor a defense that could stop it, except by Brahmadanda, a stick also created by Brahma. The Brahmastra never missed its mark and had to be used with very specific intent against an individual enemy or army, as the target would face complete annihilation. It was believed to be obtained by meditating on the Lord Brahma; it could only be used once in a lifetime. The user would have to display immense amounts of mental concentration. According to ancient Sanskrit writings, the Brahmastra is invoked by a key phrase or invocation that is bestowed upon the user when given this weapon. Through this invocation the user can call upon the weapon and use it via a medium against his adversary.
Story of Brahmastra
Since Brahma is considered the Creator in Sanatana Dharma, it is believed by Hindus that Brahmastra was created by him for the purpose of upholding Dharma (and Satya), to be used by anyone who wished to destroy an enemy who would also happen to be a part of his (Brahma’s) creation. The target, when hit by Brahmastra, would be utterly destroyed. Brahma had created a weapon even more powerful than the Brahmastra, called the Brahmashira. The Brahmashira was never used in war, as it had four times more power than the Brahmastra, i.e. Fourth power square, as the name suggests, since Brahma has Four Heads.
The weapon was also believed to cause severe environmental damage. The land where the weapon was used became barren and all life in and around that area ceased to exist, as both women and men became infertile. There was also a severe decrease in rainfall with the land developing cracks, like in a drought. The Brahmastra, described as an “iron thunderbolt,” was apparently a fairly well known weapon in the sense that scores of them were possibly made—like nuclear warheads—and were in the possession of various armies and kingdoms which occasionally desired to use them—though sometimes the gods stopped them from using these awesome weapons against each other in what seems to us today as rather petty conflicts.
There are a number of instances in Sanskrit scriptures where the Brahmastra is used—or threatened to be used. Vishvamitra used it against Vasishta, but the Brahmastra was swallowed by Brahmadanda, Lord Brahma’s countermeasure against the Brahmastra. In the Ramayana a Brahmastra is used by Shri Rama as the “final blow” against Rakshasa Ravana during their battle in Lanka. Also, Indrajit used Brahmastra against Hanuman when he was destroying the Ashok Vatika after meeting Sita. Lakshmana (Shri Rama’s younger brother) also tried to use it with Indrajit in the same battle, but Rama stopped him from using the weapon saying, “his use of the Brahamastra was not justified, nor would it benefit mankind.” It is also mentioned in vedas that Brahmastra was aimed by Shri Rama to make way out of sea so that the army of apes can march towards Lanka, however at the very moment, Varuna appeared and told Lord Rama, about the technical flaws of using the weapon and hence later was aimed towards Poorv Disha—“East Direction” by Lord Rama. Also Indrajit aimed a Bhramastra at Lord Lakshaman on the final battle between him and Lord Lakshman, however deadly weapon returned unharmed.
Prior to the Epic war of the war of the Mahabharata, Karna was planning to use the Brahmastra to fight Arjuna, but because of Parasurama's curse he was unable to do so. The Brahmastra is also used in a confrontation of Arjuna and Ashwatthama in Mahabharata, where Arjuna retracts his weapon, as ordered to do so, but Ashwatthama is unable to retract his weapon and instead sends it to attack Arjuna’s unborn grandson, named Parikshit. Parikshit. This confrontation is also said to have involved the Brahmashira, a four times more destructive weapon. In one version, Ashwatthama did not have his bow and arrow near him when he was confronted by Arjuna, so he took a piece of straw and invoking the proper phrase, or activating the weapon with a special code, he threw the straw at Arjuna, and it carried the power of the Brahmashiras.
In response, Arjuna also invoked the Brahmashira to counter Ashwatthama's—but the collision of two Brahmashiras would have destroyed the universe ! Therefore, the Rishi Vyas came bodily between the two Brahmashiras weapons, preventing them from colliding. Arjuna was able to call back his Brahmashira, but Aswathama did not know how to do this, so he commanded his weapon to attack the unborn grandchild of Arjuna, Parikshit, who is subsequently saved by the god-like powers of Krishna.
The events of the Mahabharata and the Kurukshetra War evidently take place in northern India and even Afghanistan. When the Indus Valley Civilization cities were finally excavated in the 1930s, 40s and 50s it was found that they had been completely destroyed, with people lying dead in the streets. Some sort of sudden doom had overtaken these cities, apparently killing everyone, leaving no one behind to bury the dead. This seems just like the Mahabharata’s description of the events in the Kurukshetra War.