Step 1: Why salt specifically: Salt was a daily necessity taxed and monopolized by the British, making it a powerful, universally relatable symbol of colonial injustice for Gandhi's protest.
Step 2: The journey: Starting 12 March 1930, Gandhi and 78 followers walked roughly 390 km over 24 days from Sabarmati Ashram to the coastal village of Dandi.
Step 3: The symbolic act and its ripple effect: Making salt from seawater on 6 April 1930 was a direct, illegal act of civil disobedience that triggered similar acts of defiance across the country, marking the formal start of the Civil Disobedience Movement.
Final Answer: A 390 km, 24-day salt-law-breaking march (Sabarmati to Dandi, 12 March–6 April 1930) that launched the Civil Disobedience Movement nationwide.