There might be a couple of issues here.  The first is that it is important to know that the Indian Home Rule Movement existed before Gandhi emerges on the political scene.  It is through Gandhi's immense popularity and his message that he merges the movement with the Congress party, presenting a united front against the British.  Regardless, I think that Gandhi's leadership as representing the Indian Home Rule Movement is significant because it was the first time that there was an organized and collective response towards British rule in India.  Gandhi's moral and political resistance, as seen through Congress merging with the Indian Home Rule movement, eventually signaled the end of British rule and control of India.  It started to force the issue of decolonization in real and defined terms.  The groundswell of its support around the entirety of the diverse nation helped to indicate that the subcontinent would not remain long under the control of the British.  Prior to Gandhi's emergence as both political and spiritual leader, the Indian Home Rule Movement was seen as a political organization that voiced intent that could be easily repudiated.  Yet, it is through Gandhi's popularity through populism that ended up moving him to the leadership of the movement and, combined with the Congress, ended up becoming a significant force that began the dialogue and action which results in Indian independence. The sheer force of millions of Indians on the move against the British in a manner that sought to embrace the tenets of Satyagraha were too much for the British to handle, including fighting the likes of Hitler and the Nazis.   It is through this that the British are forced to realize that their control over India, and the reality of decolonization, were inevitable.