Britain abolished its own salt tax in 1825, when the mineral became important to the manufacturing processes emerging in the Industrial Revolution [source: Le Couteur]. Nevertheless, the tax persisted in British colonies like India, where it was illegal to collect even natural deposits of salt.
To understand why the British salt tax was so oppressive to the Indian people, it helps to know a bit about the subcontinent's climate and culture. India's hot weather promotes sweating, which drains the human body of its salt supply. And because Indians don't eat much meat -- a natural source of salt -- they rely on supplementary salt to maintain a healthy amount in the body. Taxing the mineral that Indian people relied on for survival was just one way that the British government kept Indians under its thumb.
But on the morning of March 12, 1930, Gandhi set out to change that. He and 78 followers started marching from the Sabarmati Ashram toward Dandi on the Arabian Sea. More people joined the band of protesters along the journey of 240 miles (386.2 kilometers). Covering between 10 to 15 miles (16 to 24 kilometers) a day, Gandhi reached his destination in 24 days [source: Nojeim]. During the march, he stopped in villages to convince government officials to resign in protest and to encourage people to pledge nonviolence. When he got to the sea, Gandhi collected a chunk of salt, which was against the law. The act inspired a crime wave of illegal salt collection and thousands of arrests.
The frail, 61-year-old Gandhi didn't have to walk -- he could have taken a car or train to gather salt from the sea. But he knew what he was doing. His march was a symbolic protest designed to attract media attention and inspire action more than anything else. Many historians now consider it his most powerful campaign. It soon led to the Gandhi-Irwin Pact, an agreement that made it legal for people to gather and manufacture salt. What's more, the government lifted the tax a year later.
In large part due to Gandhi's campaigns of nonviolence, Britain finally awarded India independence after World War II. Gandhi's philosophy and writings have continued to inspire others, including Martin Luther King Jr., to seek change through nonviolent civil disobedience.