Du Bois, Lady Dorothea (Annesley ) (1728–74), poet, novelist, and playwright, was born in Dublin, the eldest of seven daughters of Richard Annesley (qv), Lord Altham, later 6th earl of Anglesey, and his wife, Ann (née Simpson), daughter of a Dublin merchant. In 1740 Annesley repudiated his marriage and declared his three surviving daughters illegitimate; he later married Julia Donovan, with whom he had a son, Arthur. Ann brought a suit against him in the ecclesiastical court in Dublin and was awarded alimony, but Annesley refused to pay, claiming that the marriage was rendered invalid by his prior marriage in 1715 to Ann Prust. Lady Anglesey and her daughters thereafter had no means of support but a small pension awarded to them by George II.
Dorothea grew up in Ireland and attended boarding school in Dublin. In 1752 she secretly married Peter Du Bois, a French musician who became a protestant and with whom she had six children in eight years. She embarked on a literary career to support her family and to pursue her legal claims to her patrimony. In 1760 she travelled to Wexford in an attempt to persuade her father to acknowledge her mother and sisters, but was repelled and harassed by an angry mob, an incident related in ‘A true tale’, the first of the poems collected in Poems on several occasions (published by subscription in 1764). Richard Annesley died in 1761 and his estate passed to his son Arthur. Dorothea continued to press her claims in her writing, publishing The case of Ann, countess of Anglesey, lately deceased (1766), her novel Theodora (2 vols, 1770), and her single sheet Advertisement (1767). She also wrote ‘The divorce’ (1771), a musical entertainment for Marylebone Gardens, and The lady's polite secretary, or, New female letter writer (1772), incorporating a short work on English grammar. Her play ‘The haunted grove’ was performed in Dublin, but apparently never published. Her appeals for legal redress proved unsuccessful, and she died in poverty in Dublin in 1774.