Here are the top 10 developments of the story:
Defence Minister Manohar Parrikar said in parliament this morning that he is "shocked and hurt" and that it is unfortunate that the Army is being dragged into controversy because of what he called Mamata Banerjee's "political frustration."
The Army, the minister said, was conducting a routine exercise in Bengal and other states, one which it had conducted last year in Uttar Pradesh and Jharkhand. "It is done in different states with the consent of officials," Mr Parrikar said.
A united opposition backed Mamata Banerjee's Trinamool Congress as it brought up the matter in both Houses of parliament. "We need the Army, but the army comes only after the permission of the state. They have come without the permission in West Bengal, this is an attack on the federal structure," said Mayawati of the Bahujan Samaj Party.
The Army has released letters to show that it was in communication with the West Bengal police on the annual exercise to "gather statistical data about load carriers that could be made available to the Army in case of a contingency."
The Army has also called "baseless" the Bengal government's allegation that its personnel are collecting toll at the booths from vehicles passing through.
The Kolkata Police had written back to the Army asking them not to conduct the exercise near Nabanna, the state secretariat in capital Kolkata, which also houses the Chief Minister's office. The police asked the Army to consider another spot.
On Thursday, soldiers in fatigues were seen checking vehicles at the Vidyasagar Setu toll plaza in Howrah about 500 metres away from Nabanna and Ms Banerjee tweeted, "Very unfortunate. Army stationed in front of Nabanna the Bengal State Secretariat in a high security zone, in spite of Police objection... I am waiting here at the Secretariat and watching, to guard our democracy."
The Army withdrew from the Howrah toll booth at about 11 pm on Thursday, saying it had completed the exercise there, but Ms Banerjee refused to leave, saying, "These people may have gone. But they are there in 18 other districts," she said, adding, "Don't know what will happen overnight...I will guard democracy...I will continue to be at the Bengal Secretariat till Army at all toll plazas is withdrawn."
Mamata Banerjee has alleged "political vendetta" by the Centre, with which she has clashed over the currency ban. She has led protests against the BJP-led central government's demonetisation move on the streets in national capital Delhi and in other states like Bihar and Uttar Pradesh.
In parliament, Ms Banerjee's party has joined hands with other opposition parties to disrupt both Houses since the winter session began, over the impact on people of a cash crunch that has followed the centre's ban on 500 and 1000-rupee notes aimed at curbing corruption and black or untaxed money.
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