Born in Limavady, Haslett set up business as a woollen draper in Belfast. In the 1780s, he joined the Volunteer movement. Along with other future United men, such as Thomas McCabe and William Tennant, he was a Freemason. By the 1790s he was involved in shipping, and became involved with a syndicate known as the 'New Traders'. This group espoused economic views about free trade and commerce, at odds with the system of the British Empire in the 18th century. This led them to sympathies with American Revolutionaries who shared those views, and eventually the views of democracy and republicanism. Almost all members of the New Traders would become United Irishmen.
The United Irishmen
The Society of United Irishmen was founded in 1791 in Belfast by Protestant Dissenters who, in defiance of the AnglicanAscendancy, sought a national and representative government for Ireland. Despairing of reform, inspired by Thomas Paine's ‘The Rights of Man’, and in hope of French assistance, it became a revolutionary movement. In 1791 Theobald Wolfe Tone published the pamphlet ‘Argument on Behalf of the Catholics of Ireland’ where he set out that religious division was being used to balance “the one party by the other, plunder and laugh at the defeat of both.” He put forward the case for unity between Catholic, Protestant and Dissenter to break the connection with England which maintained the Ascendancy and denied Ireland her sovereignty. Haselett was among the group of nine Belfast Presbyterians, who invited Tone and his friend Thomas Russell to Belfast to form the original society on October 14, 1791.
Imprisonment
Following the French declaration of war against Britain in 1793, the Society was outlawed and went underground. At this point, more radical members like Lord Edward Fitzgerald and the Sheares brothers came to the fore, demanding an alliance with France and an immediate national insurrection against the government. In 1796, Lazare Hoche and Wolfe Tone tried and failed to land a massive French invasion army in Bantry Bay. In response, the government and the army began cracking down on dissension and the Society. In September 1796, Haslett was arrested along with Russell, Samuel Neilson and Charles Teeling. Haslett was held for 14 months in Dublin's Kilmainham Gaol before his release in December 1797. While he was in jail two of his children died, as well as his sister who was taken ill in Dublin while coming to visit him. She was 23.
In March 1798, most of the leadership of the Leinster branch of the Society were meeting at the house of Oliver Bond in Dublin, when they were arrested. This crippled the organisation. Many of its leaders, such as Russell and Thomas Addis Emmet were already in prison, while others like Tone and James Napper Tandy were in Europe. Meanwhile, Lord Edward Fitzgerald was in hiding, with a government net closing around him. Nonetheless, in May, the rising finally began. First in Kildare, it spread to other counties in Leinster before finally consuming Ulster. Ultimately, the rising failed with enormous bloodshed. Haslett took no part in the events, yet he was still arrested again for high treason, in spite of having done much to calm tensions in the Roe Valley during the rebellion. However, by December 1799 he had been released and had returned to his business. Haseltt died in 1806, at the age of 48, and was buried in Knockbreda Cemetery, Belfast. His oration was given by his old comrade in the United Irishmen, Reverend William Steel Dickson.
