Introduction: The Rowlatt Act was a controversial law passed by the British government in India in 1919. Mahatma Gandhi, the leader of the Indian National Congress, decided to launch a nationwide movement against the act. Here are the reasons behind his decision:

Opposition to the Act: The Rowlatt Act allowed the British government to arrest and imprison Indian political activists without trial. It also restricted freedom of speech and assembly, and gave the authorities sweeping powers to suppress any form of dissent.

Violation of Human Rights: Gandhi believed that the act was a gross violation of human rights and civil liberties. He argued that it went against the principles of justice and democracy, and was a threat to the freedom and dignity of the Indian people.

Need for Nonviolent Resistance: Gandhi believed that the only way to resist the Rowlatt Act was through nonviolent means. He felt that violence would only lead to more repression and bloodshed, and that nonviolent resistance would be more effective in achieving their goals.

Unifying the Movement: Gandhi saw the Rowlatt Act as an opportunity to unify the Indian people against British rule. He felt that the act was a common threat that could bring together Hindus, Muslims, Sikhs, and other communities in India.

Challenging British Authority: Gandhi saw the movement against the Rowlatt Act as a way to challenge British authority and demand greater autonomy for India. He believed that the act was a symbol of British oppression, and that its repeal would be a significant step towards Indian independence.

Conclusion: In conclusion, Mahatma Gandhi decided to launch a nationwide movement against the Rowlatt Act because he believed that it was a violation of human rights, a threat to Indian freedom and dignity, and an opportunity to unify the Indian people against British rule. His nonviolent resistance and civil disobedience campaign ultimately led to the repeal of the act and a significant step towards Indian independence.

Mahatma Gandhi launched a satyagraha against the Rowlatt Act because of the following reasons:
1. The Rowlatt Act was an openly undemocratic measure taken by the British government. It sanctioned the detention of Indian political leaders without any trial for a period upto three years.
2. The law was passed in an autocratic fashion without considering the opinion of the Indian populace which was going to be affected by it.
3. Gandhi saw an opportunity to unite Indians against a common enemy by opposing the unjust clauses of the Rowlatt Act.