The prime factor in the emergence of modern nationalism in India was the Anti-colonial movement. This movement played a crucial role in shaping the nationalistic sentiments and aspirations of the Indian people. Here is a detailed explanation of why the Anti-colonial movement was the prime factor:

1. Historical Context:
- India had been under British colonial rule for almost two centuries. The exploitative policies of the British Raj, such as economic exploitation, cultural oppression, and political subjugation, created a sense of resentment among the Indian population.
- The impact of the 1857 Sepoy Mutiny, which was a significant uprising against British rule, further fueled the anti-colonial sentiment in the country.

2. Unifying Factor:
- The anti-colonial movement provided a common cause for Indians from diverse backgrounds to come together and fight against a common enemy. It transcended regional, religious, and caste differences, fostering a sense of unity and shared purpose among Indians.
- Prominent leaders like Mahatma Gandhi, Jawaharlal Nehru, and Subhas Chandra Bose played a pivotal role in mobilizing and organizing the masses, emphasizing the importance of unity in the struggle for independence.

3. Awakening National Consciousness:
- The anti-colonial movement acted as a catalyst in awakening the national consciousness of the Indian people. It instilled a sense of pride in India's rich cultural heritage, history, and traditions.
- The movement highlighted the injustices faced by Indians and emphasized the need for self-rule, thereby creating a strong sense of national identity and pride among the masses.

4. Adoption of National Symbols and Ideals:
- As part of the anti-colonial movement, Indians began adopting new symbols and ideals that represented their nationalistic aspirations. The national flag, national anthem, and national emblem became powerful symbols of India's struggle for independence.
- The movement also promoted new ideas such as democracy, secularism, and social equality, which became integral to the Indian nationalist discourse.

5. Mass Mobilization and Resistance:
- The anti-colonial movement witnessed massive mobilization and resistance against British rule. Protests, demonstrations, boycotts, and acts of civil disobedience became common methods used by the Indian masses to express their opposition and demand freedom.
- These acts of resistance not only challenged British authority but also strengthened the resolve and determination of the Indian people to achieve independence.

In conclusion, the anti-colonial movement was the prime factor in the emergence of modern nationalism in India. It brought together diverse sections of society, awakened national consciousness, and fostered a sense of unity and pride. Through the adoption of national symbols and ideals, the movement provided a platform for the Indian people to express their aspirations for self-rule and laid the foundation for the eventual attainment of independence.