The painting above shows a decisive moment in Irish history - the Battle of Ballynahinch, June 12, 1798. It was the last time dissenting Ulster Protestants joined with Catholic nationalists in rebellion against the British Crown.

A British officer, Captain Henry Evatt, is expiring in the foreground. But it is what’s happening around him that is really significant. The battle is all but over: the rebels have been defeated. The town of Ballynahinch is on fire and the rebels are being chased through the fields and orchards. To the left is a captured United Irishman - probably one Hugh McCullough, a grocer from Bangor, County Down. He is to be hanged soon afterwards.

This battle is significant in that is was more than just another in a long line of rebel defeats by the Redcoats. At the time Ireland had a form of Home Rule - its own parliament in Dublin. But Catholics could not vote, and Presbyterians and other dissenters were discriminated against in other ways.

Add to this dissatisfaction the heady influence of the French and American revolutions, plus opportunistic promises of military help from Britain’s arch-enemy, the French, and you have all the ingredients for a truly explosive challenge to British rule in Ireland.

But the rebellion failed. The rebels lacked arms; they had a few muskets but otherwise little more than pikes or pitchforks.

The rebels’ campaign in Ulster, and others in Dublin and Wexford, were fragmented, brave but sometimes disorganised. French intervention fizzled out, the defeated rebels were executed or transported, and the “settlement” that followed laid the ground for more rebellions and almost 30 years of recent Troubles in Northern Ireland.

The settlement involved abolishing the Irish parliament, joining Britain and Ireland by the Act of Union and postponing the emancipation of Catholics and Dissenters. The alliance gradually dissolved. New and intransigent battle-lines began to emerge - the Green, Gaelic, Catholic, separatist nationalists versus the Orange, Protestant, British-oriented unionists. Northern Ireland secretary Mo Mowlam is fully occupied with untangling the long-term consequences of 1798.

The Battle of Ballynahinch’ by Thomas Robinson is based on accounts by people he interviewed after the battle. The painting is a major set-piece in the Ulster Museum’s 1798 commemorative exhibition, ‘Up in Arms’, which opened on April 3 and runs until August 31.

During the summer there will be a series of events and talks at the museum about aspects of 1798 and a chance to hear - and hear about - the ballads of 1798. For party bookings, telephone the Ulster Museum on 01232 383030