Step 1: Recall the year directly:
1931 A.D. marks: Gandhi-Irwin Pact.
Step 2: Provide brief context:
The Gandhi-Irwin Pact was signed in March 1931 between Mahatma Gandhi and Viceroy Lord Irwin, leading to the suspension of the Civil Disobedience Movement and Gandhi's participation in the Second Round Table Conference.
Final Answer:
\[ \boxed{\text{Gandhi-Irwin Pact}} \]