It is the belief of traditional Indian nationalists that the events of 1857 are not a series of isolated and uncoordinated mutinies. In fact, it was a war of idependence for achieving freedom.
It is a turning point in which the nationalist feeling, long suppressed by the British occupation flared into violence. It convinced the Britishers that India could not be held at leisure and fear of another mutiny continued to haunt the British rulers right till 1947. That is why a lot of people consider the mutiny of 1857 as the "First war of Independence".