Samudragupta was the greatest of the rulers of the Gupta dynasty. The Allahabad Pillar inscription provides a detailed account of his reign. It refers to three stages in his military campaign:
Against some rulers of North India
His famous Dakshinapatha expedition against South Indian rulers
A second campaign against some other rulers of North India.
In the first campaign Samudragupta defeated Achyuta and Nagasena. Achyuta was probably a Naga ruler. Nagasena belonged to the Kota family which was ruling over the upper Gangetic valley. They were defeated and their states were annexed. As a result of this short campaign, Samudragupta had gained complete mastery over the upper Gangetic valley.
Then Samudragupta marched against the South Indian monarchs. The Allahabad Pillar inscription mentions that Samudragupta defeated twelve rulers in his South Indian Expedition. They were Mahendra of Kosala, Vyaghraraja of Mahakanthara, Mantaraja of Kaurala, Mahendragiri of Pishtapura, Swamidatta of Kottura, Damana of Erandapalla, Vishnugupta of Kanchi, Nilaraja of Avamukta, Hastivarman of Vengi, Ugrasena of Palakka, Kubera of Devarashtra and Dhananjaya of Kushtalapura. Samudragupta's policy in South India was different. He did not destroy and annex those kingdoms. Instead, he defeated the rulers but gave them back their kingdoms. He only insisted on them to acknowledge his suzerainty.
The third stage of Samudragupta's campaign was to eliminate his remaining north Indian rivals. He fought against nine kings, uprooted them and annexed their territories. They were Rudradeva, Matila, Nagadatta, Chandravarman, Ganapathinaga, Nagasena, Achyuta, Nandin and Balavarman. Most of these rulers were members of the Naga family, then ruling over different parts of north India.
After these military victories, Samudragupta performed the asvamedha sacrifice. He issued gold and silver coins with the legend 'restorer of the asvamedha'. It is because of his military achievements Samudragupta was hailed as 'Indian Napoleon'.
After these conquests, Samudragupta's rule extended over the upper Gangetic valley, the greater part of modern U.P., a portion of central India and the southwestern part of Bengal. These terri-tories were directly administered by him. In the south there were tributary states. The Saka and Kushana principalities on the west and northwest were within the sphere of his influence. The kingdoms on the east coast of the Deccan, as far as the Pallava Kingdom, acknowledged his suzerainty.
Samudragupta's military achievements remain remarkable in the annals of history. He was equally great in his other personal accomplishments. The Allahabad Pillar inscription speaks of his magnanimity to his foes, his polished intellect, his poetic skill and his proficiency in music. It calls him Kaviraja because of his ability in composing verses. His image depicting him with Veena is found in the coins issued by him. It is the proof of his proficiency and interest in music. He was also a patron of many poets and scholars, one of whom was Harisena. Thus he must be credited with a share in the promotion of Sanskrit literature and learning, characteristic of his dynasty. He was an ardent follower of Vaishnavism but was tolerant of other creeds. He evinced keen interest in Buddhism and was the patron of the great Buddhist scholar Vasubandu.