‘Salt March’ became an effective tool of resistance against colonialism because:Mahatma Gandhi found in salt a powerful symbol that could unite the nation.
Gandhiji sent a letter to Viceroy Irwin stating eleven demands. The most stirring of all was the demand to abolish the salt tax.
Salt was the most essential item of food and was consumed by rich and poor alike.
Irwin was unwilling to negotiate, so Gandhiji started Salt March with 78 volunteers. (On 6th April ) he reached Dandi, violated law and made salt.
This March developed the feeling of nationalism, people in different parts of the country broke the salt law and manufactured salt and demonstrated in front of government salt factories.