Gandhiji launched the Non-cooperation movement of 1921 because: 
According to Gandhiji, the British rule was established in India with the cooperation of Indians and had survived only because of this cooperation. So the time has arrived to withdraw cooperation from the British. 
First World War added to the misery of the Indian people. Heavy taxes, high prices, famines, and epidemics made people's life miserable. 
Rowlatt Act invited large scale protests throughout the country. 
Jallianwala Bagh Massacre and the injustice done to Punjab made Indians angry which needed to be avenged.
To restore the status of the ruler of Turkey. 
To bring Swaraj or Self Rule to India. 
In this way, the reasons for launching the non-cooperation movement were all-inclusive, and it because of this that the movement united everyone in the country.

Introduction:
Mahatma Gandhi, the father of the Indian nation, launched the Civil Disobedience Movement and the Non-Cooperation Movement as a means to unite the country and fight against British colonial rule. These movements played a significant role in the Indian independence struggle and had a profound impact on the mindset of the people.

1. Civil Disobedience Movement:
The Civil Disobedience Movement was initiated by Mahatma Gandhi in 1930 as a protest against the British-imposed salt tax. The movement aimed to challenge the unjust laws and policies of the British government through nonviolent resistance and civil disobedience.

2. Non-Cooperation Movement:
The Non-Cooperation Movement was launched by Gandhi in 1920 as a response to the Jallianwala Bagh massacre and other oppressive measures by the British government. The movement called for Indians to boycott British institutions, including schools, courts, and government offices, and to refuse to pay taxes.

Reasons for launching the movements:
- Unity: One of the primary objectives of Gandhi's movements was to unite the diverse Indian population under a common cause. By mobilizing people from different regions, religions, and social backgrounds, Gandhi aimed to create a sense of national unity and solidarity among Indians.

- Mass participation: Gandhi believed in the power of mass participation in nonviolent resistance. Through these movements, he aimed to involve ordinary Indians in the struggle for independence, empowering them to challenge British authority and contribute to the freedom movement.

- Nonviolence: Gandhi strongly believed in the philosophy of nonviolence and passive resistance. He saw these movements as a means to demonstrate the effectiveness of nonviolent methods in achieving political objectives. By adhering to nonviolence, Gandhi aimed to set an example for future generations and create a moral high ground in the struggle against British rule.

- Self-reliance: Gandhi emphasized the importance of self-reliance and self-sufficiency for India's progress. Through the boycott of British goods and institutions, he aimed to promote Indian industries and foster economic independence. This focus on self-reliance was not only a means to challenge British rule but also a path towards India's overall development.

Impact and significance:
- The movements led by Gandhi played a crucial role in galvanizing the masses and awakening a sense of national consciousness. They brought people from different backgrounds together, fostering a spirit of unity and collective action.

- The movements also had a profound impact on the British rulers, who were forced to confront the widespread discontent and growing resistance. This ultimately contributed to the weakening of British colonial control and paved the way for India's independence.

- Gandhi's emphasis on nonviolence and civil disobedience inspired many other leaders and movements around the world, becoming a powerful tool for social and political change.

- The movements helped in creating a political awakening among the masses, encouraging them to actively participate in the struggle for independence. They also instilled a sense of self-confidence and self-belief in the Indian population, who realized their collective strength against the mighty British Empire.

In conclusion, Mahatma Gandhi launched the Civil Disobedience Movement and Non-Cooperation Movement to unite the country and fight against British colonial rule. These movements aimed to mobilize the masses, promote unity, and challenge British