Why was ghandi able to achieve independence through his methods?
Because by then, United Kingdom knew that their military power were on the wane. Look at the case of Malaya and Singapore, the British forces surrendered to the marching Japanese armies without a fight. British forces did well against tribal units using primitive weapons like swords and spears, but never had any significant success against modern, well organised armies. The tide of nationalistic fervour fighting for independence in many colonies weighed against the overall strategy of concentrating on contingency emergency at home front, against communist states in Eastern Europe. Decline of the British Empire had already begun . . . . and till today, Britain has no choice but to hide under the umbrella of NATO, for Britain fears reprisal from rising powers like China.