In the rebellion year of 1798, an uncle, John Moore, was named President of the Government of the province of Connaught in Castlebar by General Humbert during its brief occupation by the French.

[2][3] Moore was educated in England at St Mary's Catholic preparatory school in Oscott, near Birmingham, before entering Christ's College, Cambridge in 1827.

Together with the Marquess of Sligo and Sir Robert Lynch-Blosse, from the United States he imported 1,000 tonnes of flour for distribution among tenants at half cost.

[6] He tried, and failed, at a Dublin convention to get his fellow Whigs to oppose their leadership at Westminster, the government of Lord John Russell, and protest the laissez-faire approach to the agrarian crisis maintained by Treasury secretary Charles Trevelyan.

A close friend of Archbishop John MacHale of Tuam, Moore took the leading role in establishing (August 1851) the Catholic Defence Association (CDA).

On 28 October 1852, with the support of twenty-six MPs, Moore also established in Dublin the short-lived Friends of Religious Freedom and Equality to call for the disestablishment of the Church of Ireland.

At his insistence, and by prior agreement, they sat as the Independent Irish Party, pledged to support no government that did not both advance tenant rights and revoke the Ecclesiastical Titles Act.

Finding that, with a number of other CDA members, they held the balance of power in the House of Commons, they voted for, and accepted offices in, a new Whig-Peelite ministry in return for a commitment on the church question alone.

[10] Moore continued to put pressure on MPs to adopt the independent opposition policy by using the influence of the Tenant League, of which he was chairman during 1856.

During the late 1850s he also made repeated unsuccessful attempts to persuade the Young Ireland veteran William Smith O'Brien to re-enter Irish politics and lead the independent party.

[12] Moore refused to back Cullen's preferred alternative to the independent opposition, the National Association of Ireland (established 29 December 1864).

Instead, with the encouragement of Archbishop MacHale, in 1868 Moore stood again for parliament in Mayo as a Liberal on a platform of tenant right and amnesty for Fenian prisoners.

Although he had himself, according to John Devoy, been denied entry into the Irish Republican Brotherhood by James Stephens in 1864, he began conferring regularly with some IRB leaders.

[16] A few months before his journey back to Ireland, Moore had been forwarded a copy of a note red ink that was being circulated to tenants on the outlying Ballintubber estate of his 12,481 acre property: "IMPORTANT.