Holding aloft 15,000 party flags and 3,000 tricolours which fluttered on a chilly winter afternoon, the BJP workers and top state party leaders marched from Subodh Mallick Square in the city hub to near revolutionary leader Netaji Subhas Chandra Bose's statue at Shyambazar Five Point Crossing in North Kolkata in an impressive show of strength.

Led by the party's Working President J.P. Nadda in an open jeep, with other top state party leaders walking on the road, the Bharatiya Janata Party's 'Abhinandan Yatra' (Thanksgiving rally) was organised to thank Prime Minister Narendra Modi for passing the Citizenship Amendment Act, which the party hopes would have a huge bearing in the eastern state by giving citizenship to lakhs of refugees - mainly Bengali Hindus - who came as refugees to West Bengal from East Pakistan (later Bangladesh).

Impressed with the size of the rally, Nadda said: "We've seen several changing possibilities in Bengal in the past. Today's picture, though, was unprecedented."

"The energy was infectious and it took us three hours to reach here. We can clearly see that change is coming to the State," he said addressing party workers at Shyambazar.

He said the sea of people present proves that they stand in tow with Modi and support the CAA.

There were thousands of posters and banners supporting CAA and running down Banerjee and the state's Trinamool Congress, but the most raucous sloganeering was targeted at the Chief Minister.

"Didi (elder sister - as Banerjee is called) tumi chole jao, Pakistane chole jao (Didi you please go, to Pakistan you go)," "Ei Mamata dekhe ja, BJP-r khamata (Didi come and see, BJP's ability you must see)", found great resonance among the participants, particularly youths and students who were in a majority.

Several posters carried pictures of Syama Prasad Mookerjee - the founder of BJP's precursor Jana Sangh - as also those of Modi and Union Home Minister Amit Shah, and repeated slogans were heard eulogising them.

All senior BJP leaders in the state - President Dilip Ghosh, national executive member Mukul Roy, Union ministers Babul Supriyo and Debosree Chowdhury, party national General Secretary Kailash vijayvargiya as also others took part in the march which got the police nod late on Sunday night after days of negotiations involving authorities and senior party leaders. The BJP leaders had earlier threatened to rollout the programme irrespective of whether they get police permission or not.

The Matuas and Namashudras -- Hindu lower caste people who migrated to West Bengal from East Pakistan and later Bangladesh as refugees -- were present in strength in the rally, besides Sikhs and a "large number of Muslims".

The Matuas and Namashudras are expected to be "formally given citizenship after the passing of the Act". However, BJP's opponents have claimed that these groups have been enjoying all citizenhip facilities for decades.

Lending colour to the rally, 15 tableaux were positioned highlighting various aspects of the CAA to create public awareness on the issue.

Some of the tableaux tried to bring out the 'double speak' of Banerjee "who had so loudly raised in the Rajya Sabha the issue of infiltration from Bangladesh in 2005, only to do a volte face now for the sake of her vote bank", a BJP leader said.

In view of the vandalisation of the statue of polymath Ishwar Chandra Vidyasagar on the day of party President Amit Shah's rally in the city during the Lok Sabha poll campaign earlier this year, the BJP leadership deployed a large number of volunteers to manage the crowd all along the route.

The party also garlanded the statues of a number of eminent persons on the route.

The rally was called in the aftermath of widespread violent protests in the state against the new citizenship law, with the agitators vandalising and torching trains and railway stations and blockading railway tracks and highways.

Since Monday, Chief Minister Banerjee has hit the streets, holding processions and meetings drawing huge crowds and involving sections of civil society.