The major cause of Gandhi's independence movement in India was the fact that the British had colonized India and were ruling it for the benefit of Britain rather than for the benefit of the Indians. (They also tended to keep essentially all the top jobs in the government for British only, regardless of the qualifications of Indians.) British rule grew more and more annoying to Indians over the years, especially as more of them became educated.
The major effect of Gandhi's movement, of course, was that India won its independence in 1947. I suppose that you could say that a secondary impact was the partition of India and Pakistan that occurred in that same year. The independence movement had been largely separated along religious lines and that helped cause a strong desire among Muslims to have their own country.