His great-grandfather was Nicholas Brown Sr. (1729–1791), a merchant and slave trader who co-founded the College in the English Colony of Rhode Island and Providence Plantations.

[10][11] He prepared for college with private tutors, including William Carey Poland,[12] and later enrolled at Brown University with the class of 1885.

In their business dealings, Harold and John relied upon George W. R. Matteson, the trustee of their father's estate for advice and assistance.

After hearing of his brother's death,[21] Harold immediately headed home from a trip in Europe with his wife, only to himself die a few days, aged 36, later upon his return to America.

[1] Both Harold and his brother willed their estates to his nephew, who became the heir of his family's fortune and was referred to as the richest child in the world at the time.