Why do the historians regard the Uprising of 1857 as the First War of Independence?

The historians regarded the Uprising of 1857 as the First War of Independence because:

1. It was the first mass uprising in which all the sections of Indian society participated against a common enemy, i.e., the British.
2. It paved the way for the rise of modern national movement. The sacrifices made by Laxmi Bai, Nana Saheb and Mangal Pandey served as a source of inspiration to the leaders and people to fight for the independence of India from the British rule.