Dhanur Veda is the education on Military Training. The Vishnu Purana text describes Dhanur Veda as one of the traditional eighteen branches of knowledge. Though some descriptions of Dhanur Veda are found in Vedic and epic literature, and in other ancient texts such as the Vishnu Purana and the Siva Dhanur Veda of the Gupta Empire, the earliest extant manual of Dhanur Veda is in the Agni Purana (c. 8th century), which contains several chapters giving descriptions and instructions on the fighting arts of Dhanur Veda, with reference earlier sutras on Dhanur Veda dating back centuries earlier. It described how to improve a warrior's individual prowess and kill enemies using various different methods in warfare, whether a warrior went to war in chariots, elephants, horses, or on foot.
Foot methods were subdivided into armed combat and unarmed combat. The former included the bow and arrow, the sword, spear, noose, armour, iron dart, club, battle axe, discus, and the trident. The latter included wrestling, knee strikes, and punching and kicking methods.
Dhanur-veda, or military science, was taught by Droṇācārya with all its confidential secrets of throwing and controlling by Vedic hymns. Gross military science is dependent on material weapons, but finer than that is the art of throwing the arrows saturated with Vedic hymns, which act more effectively than gross material weapons like machine guns or atomic bombs.
The control is by Vedic mantras, or the transcendental science of sound. It is said in the Rāmāyaṇa that Mahārāja Daśaratha, the father of Lord Śrī Rāma, used to control arrows by sound only. He could pierce his target with his arrow by only hearing the sound, without seeing the object. So this is a finer military science than that of the gross material military weapons used nowadays. Arjuna was taught all this, and therefore Draupadī wished that Arjuna feel obliged to Ācārya Droṇa for all these benefits. And in the absence of Droṇācārya, his son was his representative. That was the opinion of the good lady Draupadī. It may be argued why Droṇācārya, a rigid brāhmaṇa, should be a teacher in military science. But the reply is that a brāhmaṇa should become a teacher, regardless of what his department of knowledge is. A learned brāhmaṇa should become a teacher, a priest and a recipient of charity. A bona fide brāhmaṇa is authorized to accept such professions.
Even the department of military education (Dhanur-veda) was also taken up by such intelligent men, and the vipras were also teachers of this section of knowledge, as were Droṇācārya, Kṛpācārya, etc.