Answer by taking a quote from the following article:

Brahmabandhab Upadhyay was born as Bhavani Charan Bandyopadhyay in a Kulin Brahmin family. The term Kulin indicates to a cult in barhmanical Hindu society of early era when a person was allowed to marry any number of wives. His grand father was known to have married fifty six wives. His father, Debi Charan Bandyopadhyay was a police officer of the British regime.

While Bramhabandhab was in Brahmosamaj, he initiated a boys' school in Sindh in the year 1888. He also taught for some time in Union Academy, which was established 1887 as the "Bengalee Boys High School" founded in Shimla under the chairmanship of Sir Nripendra Nath Sircar. He brought out a monthly journal titled The Twentieth Century in association with Nagendranath Gupta (1861-1940). Brahmabandhab and his disciple Animananda started a school in Kolkata in 1901 . Aim of the school was to teach and propagate the Vedic and Vedantic ideas of life along with modern education among the elite class of the society. Rabindranath tagore was very much attracted to this idea of reviving the old Indian ideal of paedagogy, and offered them to shift their school to Santiniketan in his father's estate. This way Tagore's school at Shantiniketan was conceived, which later became known and famous as Viswa Varati. There were three teachers, namely Reba Chand, Jagadananda Roy and Shibdhan Vidyarnab, apart from Rabindranath and Brahmabandhab, and there were five students, namely, Rathindranath Tagore, Gourgobinda Gupta, Premkumar Gupta, Ashok Kumar Gupta and Sudhir Chandra Nun. This collaboration could not continue for long and in 1902 Brahmabandhab and Animananda left Shantiniketan. During 1902 to 1903 Brahmabandhab toured Europe. He lectured in Oxford and Chembridge Universities and preached Vedantism. When he came back, he saw Bengal as a hot seat of political activities, and he too fervently plunged into the political doldrums. he was gradually coming to the conclusion that before India could become Catholic, she must be politically free. His journal "Sofia" soon became the strongest critique of the British imperialism.

what other activites was he involved in?
He lectured in Oxford and Chembridge Universities and preached Vedantism.