The Bangladesh liberation war is an epic itself. The atrocities of Pakistani Army were countered and fought by Mukti Bahini (freedom fighters) initially in March 1971 and in the later stage (in December) Indian Army engaged in the war directly. Although India trained Mukti Bahini and provided arms from much earlier.

Now there are certain quarters in Bangladesh who try to ignore India's contributions and some think that it was India's game plan to divide Pakistan, their arch rivals. And interestingly there are some quarters in India who thinks that it was Indian army's might alone that liberated Bangladesh. Mukti Bahini and the civilians had little role to play.

I would urge both the quarters to read a real freedom fighters tale. Shah Zaman Mozumder explains the role of Indian army in Bangladesh:

From the month of September, the Indian army gradually started to participate directly in the Liberation War. Initially the support was limited to indirect fire support (artillery support) to Mukti Bahini units. From November, the Indian army was permitted to conduct operations up to 10 miles inside Bangladesh territory. This was to clear Pakistan army positions from the borders areas in preparation for the December war.

The final war in December was primarily fought by the Indian army units. The Mukti Bahini units were responsible to provide second tier support to the Indian formations.

I feel ashamed at our ungratefulness as a nation. Is it not possible to acknowledge the Indian martyrs during our victory celebrations —those who sacrificed their lives in the foreign soil of Bangladesh? Are we afraid that acknowledging Indian assistance will make our contributions less significant?

India did not give us freedom. India helped in our freedom struggle and as a self respecting nation we must acknowledge that.

I don't think that will overshadow the contributions (the deserving ones) of others.

Now another controversy is brewing in India about who ordered the final march towards Dhaka that led to the surrender of Pakistan army. Praveen Swami writes in the Hindu that it was then Chief of Staff of the Eastern Command, Major-General J.F.R. Jacob's decision rather than a direct order of Army Chief Sam 'Bahadur' Manekshaw.

Niraj explains:

Soon after deciding to enter the fray, the Indian Army’s initial goal was to capture and secure the western half of Bangladesh (then East Pakistan). Any further advancement could have led to a Pakistani counterattack towards India's borders. It didn't matter in the end. Both the United States and China, after some sabre-rattling, did not interfere as first feared; and the Indian Army made better then expected progress on the ground, so the decision to capture Dhaka was almost an afterthought.

This can be verified by the official archive of the Bangladesh War, 1971, which is still classified by the Indian government.