Here is what Sri Aurobindo himself said (in third person) when asked about the idea of Bhawani Mandir.
‘Bhawani Mandir was written by Sri Aurobindo but it was more Barin’s idea than his. It was not meant to train people for assassination but for revolutionary preparation of the country. The idea was soon dropped as far as Sri Aurobindo was concerned, but something of the kind was attempted by Barin in the Maniktala Garden and it is to this evidently that Hemchandra refers.
[An attempt was made to find a site where the Bhawani Mandir idea could be put into operation; later the plan was dropped.]
Sri Aurobindo does not remember anything of this kind nor of any formal decision to abandon the Bhawani Mandir idea. This selection of a site and a head of the monastery must have been simply an idea of Barin. He had travelled among the hills trying to find a suitable place but caught hill-fever and had to abandon his search and return to Baroda. Subsequently he went back to Bengal, but Sri Aurobindo did not hear of any discovery of a suitable place. Sakaria Swami was Barin’s Guru: he had been a fighter in the Mutiny on the rebel side and he showed at the breaking of the Surat Congress a vehement patriotic excitement which caused his death because it awoke the poison of the bite of a mad dog which he had reduced to inactivity by a process of his Yogic will; but Sri Aurobindo would not have chosen him for any control of the political side of such an institution. The idea of Bhawani Mandir simply lapsed of itself. Sri Aurobindo thought no more about it, but Barin who clung to the idea tried to establish something like it on a small scale in the Maniktala Garden.’
(Ref. https://incarnateword.in/cwsa/36/bhawani-mandir)
So as you can see, this piece written during the revolutionary days was not entirely Sri Aurobindo’s own idea. It was conceived by his brother along the lines of the revolution by the Sanyasis, as indicated in the famous novel of Bankim Chandra ‘Bande Mataram’. The temple, though conceived also as a physical space in the hills to house the revolutionaries was never actually pursued. Nor did Sri Aurobindo ever actually want a physical temple to be built for Bhawani. Bhawani here refers to the Universal Mother as Durga, who is the guardian deity of India and represents India’s soul. As he indicates clearly in the Durga strota, the temple has to be built first and foremost within us.
‘Mother Durga! Enter our bodies in thy Yogic strength. We shall become thy instruments, thy sword slaying all evil, thy lamp dispelling all ignorance. Fulfil this yearning of thy young children, O Mother. Be the master and drive thy instrument, wield thy sword and slay the evil, hold up the lamp and spread the light of knowledge. Make thyself manifest.
Mother Durga! When we possess thee, we shall no longer cast thee away; we shall bind thee to us with the tie of love and devotion. Come, Mother, manifest thyself in our mind and life and body.
Come, Revealer of the hero-path. We shall no longer cast thee away. May our entire life become a ceaseless worship of the Mother, all our acts a continuous service to the Mother, full of love, full of energy. This is our prayer, O Mother, descend upon earth, make thyself manifest in this land of India.’
(Ref. https://incarnateword.in/cwsa/09/hymn-to-durga#p11)
Affectionately,
Alok Da
