Drennan was born in Rosemary Street, Belfast in 1754 to an important Presbyterian family; his father was the Presbyterian Minister and political reformist Thomas Drennan. William followed in his father’s early footsteps by pursuing a medical degree in Scotland. Upon his return from Edinburgh University, William moved to Newry in 1872 to open his own medical practice. Here, he worked as an accoucheur (male midwife) for nearly 20 years. This would have been an unusual medical specialism for William at the time, given that childbirth was seen largely as a separate female concern. During this time, William developed advanced ideas about disease. He stressed the link between a lack of handwashing and disease nearly 100 years before Louis Pasteur formally developed the germ theory in 1861. Drennan was also an early advocate for inoculations against smallpox; he presented his paper on inoculations to a committee meeting at the Poor House in 1782. He had developed this theory by testing inoculations on willing residents of the Poor House. Edward Jenner is now credited as being the pioneer of the vaccine, despite his efforts being over 10 years after Drennan’s. He continued his successful work with women and children after moving to Dublin in 1790. 

   Alongside an advanced medical career , Drennan also engaged in fruitful political ventures. He had joined the Irish Volunteers, a group formed in 1778 to defend Ireland against a French Invasion. During this time he published poetry with strong nationalist messages, for example ‘The Letters of an Irish Helot’ in 1785. He was also central to a later grassroots movement; the United Irishmen. The group formed in 1791 in retaliation to England’s governance in Ireland, they demanded, alongside other things, Catholic emancipation and joint governance in Ireland. Drennan was initially very actively involved, serving as the group’s first president. However, following his arrest for seditious activity in 1794 and subsequent time in jail his involvement faded out. He did, however, continue to write rousing, nationalist, political poetry throughout. Including ‘When Erin First Rose’ where Ireland is, for the first time, described as the ‘Emerald isle’.  

   After largely withdrawing from political life Drennan focused on other ways in which he could promote the co-operation of Catholic and Protestant people in Ireland. He was a key founder of the Belfast Academical Institution (‘Inst) in 1810, which aimed to be co-educational across the religious divide. To the last, he was dedicated to religious equality in Ireland. Following his death in 1820, Drennan requested that his coffin be carried by an equal number of Catholics and Protestants and that clergy from different denominations officiated. His remains lay in the Clifton Street Graveyard where his gravestone is inscribed with a passage of his poetry; ‘Pure, just, benign thus filial love would trace, the virtues hallowing this narrow space, The Emerald Isle may grant a wider claim, and link the Patriot with his countrys name’. He is buried alongside his beloved sister and confidant Martha McTier, with whom over 1,400 letters of their correspondence has been retained and subsequently reprinted. The letters have since proven an important source for historians understanding Irish politics and social history, and continues the legacy of Drennan and McTier into the modern day!