Name the famous Pact that demonstrated the unity between the Congress and the Muslim League. When was it signed?

The LUCKNOW PACT, signed in 1916 at the Lucknow session.

By it the Congress and the Muslim League agreed on a joint scheme of constitutional reform and demanded self-government; the Congress accepted separate electorates for Muslims. It was negotiated largely by Tilak and Jinnah, and the same session also reunited the Early and Assertive Nationalists after the Surat Split of 1907.

One mark for the name and one for the year. Two facts make the answer complete: the Congress ACCEPTED separate electorates (a concession with long consequences), and the same 1916 session healed the split of 1907. Papers ask about both. Jinnah was then a Congress member as well as a Leaguer, and was called "the ambassador of Hindu-Muslim unity" — an irony worth knowing.