Jeremiah O’Donovan Rossa was born Jeremiah O’Donovan in Roscarbery, West Cork on 10 September 1831. He took the appendage Rossa at a later date in deference to the family’s perceived Celtic roots in the Rossmore area of Cork. His family were hit hard by the famine of 1845-52 and suffered greatly. They lost their linen bleaching business, all the money they had was used to pay their rent and the family risked starvation and eviction. He later described their plight:
"I did not know how my father felt, I did not know how my mother felt; I did not know how I felt myself. There were four of us children. The potato crop had gone. The wheat crop had gone".
To relieve his family’s distress Rossa’s father, Denis, took a job as a supervisor with the Board of Works. Working on a road through Rory Glen, he employed Rossa as one of his workers. However, Denis O’Donovan contracted famine fever and died on 25 March 1847 leaving the family penniless. The famine had a profound impact on the young Rossa and influenced his Republicanism. This was represented by his best-known poem ‘Jillen Andy’, which written twenty years later graphically illustrated the horrors of the Famine. To the end of his life Rossa refused to acknowledge that the Famine was an act of God, considering it a blasphemy to blame God. He believed that the British government was to blame, and that they were ‘worse than the demons of Hell’.
In 1856 Rossa was a founding member of the Phoenix National and Literary Society in Skibbereen, West Cork. He chose its name in deference to the Phoenix, famed for its ability to rise from the ashes and saw this as representing Ireland rising phoenix-like once again. The society grew throughout the area, its members were nationally minded and disaffected with the nature of British rule in Ireland. Within two years of its foundation a further organisation had been established in Dublin, 17 March 1858, known as the Brotherhood and later the Irish Republican Brotherhood (IRB). Rossa was an early recruit to the IRB and facilitated a merger between the two societies. He recalled how ‘we were not long working when a great change was noticeable in the temper of the people. In the cellars, in the woods, and on the hillsides, we had our men drilling in the night time, and wars and rumours of wars were on the wings of the wind.’ He was not long at work when, based on the information of an informer within the Phoenix Society, he was arrested and imprisoned in Cork Jail and was held without trial until July 1859. Rossa remained active within the IRB and in May 1863 left Ireland for New York City on Fenian business, returning home later that year on foot of an offer to be involved with an IRB newspaper, The Irish People.