During the 1840s Dillon rose to prominence as an Irish nationalist politician and journalist, helping to launch the Nation in 1842, and taking a leading role in the Irish Confederation from 1847. He participated in the Young Ireland insurrection of 1848, after which he fled to New York, where he prospered as a lawyer and remained aloof from Irish politics.
By now a constitutional nationalist, and an ardent, though liberal, Catholic, Dillon helped to found the National Association in December 1864, becoming its leading lay member and first secretary.
Dillon was a constant attendee at Westminster, but, appearing ‘to regard his first session in Parliament as a sort of apprenticeship’, sat on just one select committee.
Having given evidence to the select committee on the Tenure and Improvement of Land (Ireland) Act in May 1865, in which he emphasised ‘the immediacy with which the Irish people continued to feel their historic dispossession’ and the central role which the land question (and security of tenure in particular) continued to play in Irish electoral politics, he was credited with responsibility for the ‘great advance’ made in the tenant’s cause the following session.
Regarded as both prudent and magnanimous, Dillon was widely respected and said to have been trusted by the Irish hierarchy ‘more than any other politician since O’Connell’.
As ‘an ardent advocate of Reform for England as well as for Ireland’, Dillon endeavoured ‘to bring about a cordial understanding and union’ between English and Irish Liberals, thus helping to pave the way for the era of Gladstonian reform.
