Which Indian ruler from ancient history is often described by historians as the Napoleon of India because of his extensive and successful military campaigns across northern India?

Introduction / Context:
This question is from ancient Indian history and focuses on the military achievements of major rulers. Historians sometimes compare Indian kings with famous foreign figures to highlight particular qualities. The phrase Napoleon of India refers to a king whose campaigns were swift and wide ranging, similar to those of Napoleon Bonaparte in Europe.

Given Data / Assumptions:
- The nickname in question is Napoleon of India.
- It comes from modern historians, not from inscriptions of the time.
- The options list Ashoka, Samudragupta, Chandragupta Maurya, Harshavardhana, and Pulakeshin II.
- We assume some knowledge of each ruler conquests and style of rule.

Concept / Approach:
Samudragupta of the Gupta dynasty is famous for a long list of military conquests. The Allahabad pillar inscription, composed by Harisena, describes his campaigns across northern India, central India, and parts of south India. Because of his vigorous expansion and military success, some historians, such as Vincent Smith, referred to him as the Napoleon of India. The other rulers also had significant achievements but are associated with different reputations and titles.

Step-by-Step Solution:
Step 1: Recall that Ashoka is mainly remembered for adopting Buddhism and promoting non violence after the Kalinga war, not for being compared to Napoleon. Step 2: Chandragupta Maurya founded the Mauryan Empire and defeated the Nanda dynasty and the forces of Seleucus, but he is not commonly called Napoleon of India. Step 3: Harshavardhana ruled north India in the seventh century but did not expand to the same extent as Samudragupta, and the title is not linked with him. Step 4: Samudragupta is widely known for his conquest campaigns recorded in the Allahabad pillar inscription, leading historians to liken him to Napoleon. Step 5: Therefore, the correct answer is Samudragupta.

Verification / Alternative Check:
A helpful verification is to connect each ruler with a key description used in history texts. Ashoka is associated with the title Devanampriya and with rock and pillar edicts. Chandragupta Maurya is linked with Chanakya and the foundation of the Mauryan Empire. Harsha is linked with the writer Banabhatta and the book Harshacharita. Samudragupta is consistently described as an outstanding conqueror, and the phrase Napoleon of India appears in many introductions to the Gupta period, confirming the correct option.

Why Other Options Are Wrong:
Ashoka emphasised dharma and renounced aggressive warfare after Kalinga, so he is not compared to Napoleon, who is known for continuous wars.
Chandragupta Maurya created a large empire but is not given the specific label Napoleon of India in standard textbooks.
Harshavardhana had military achievements but did not match the geographic spread and campaign style that led to the comparison used for Samudragupta.
Pulakeshin II defeated Harshavardhana in the south but is not commonly called Napoleon of India in exam oriented materials.

Common Pitfalls:
Students sometimes confuse Samudragupta and Chandragupta because they belong to different dynasties with similar sounding names. Another mistake is to pick Ashoka simply because he is the most famous Mauryan ruler. To avoid confusion, link Samudragupta with the Allahabad inscription and with the phrase Napoleon of India, which highlights his role as a great military conqueror.

Final Answer:
The ruler known as the Napoleon of India is Samudragupta.