Step 1: Give the trigger directly:
The Khilafat Movement arose from Indian Muslim anger at the post-WWI threat to the Ottoman Caliph's position.
Step 2: Give the leadership and the alliance with Congress:
Led by the Ali brothers, it was strategically joined by Gandhi and the Congress to the Non-Cooperation Movement, forging Hindu-Muslim unity against British rule.
Step 3: Give its outcome:
It lost momentum once Turkey itself abolished the Caliphate in 1924.
Final Answer:
\[ \boxed{\text{A Muslim-led agitation (1919-24) to save the Ottoman Caliphate, allied with Gandhi's Non-Cooperation Movement}} \]