The Irish Republic more commonly referred to as the Republic of Connacht was a short-lived Irish breakaway puppet state established with French Directory military support for 13 days during the Irish Rebellion of 1798.

Below is an excerpt from the proclamation of General Humbert, the French General who led the French and Irish armed forces in the short-lived Republic. The proclamation was made on 22 August 1798, the day the General first landed in County Mayo:

LIBERTY, EQUALITY, FRATERNITY, UNION – After several unsuccessful attempts, behold at last Frenchmen arrived amongst you… Brave Irishmen, our cause is common. Like you we hold as indefeasible the right of all nations to liberty. Like you we are persuaded that the peace of the world shall ever be troubled as long as the British ministry is suffered to make with impunity a traffic of the industry and blood of the people . . . Union, Liberty, the Irish Republic! Such is our shout. Let us march. Our hearts are devoted to you; our glory is in your happiness.

The above decree refers to an Irish Republic, not a Republic of Connacht. Hence, strictly speaking, it appears to be incorrect to refer to any formal establishment of a Republic of Connacht. Instead, an Irish Republic had been proclaimed. On 31 August 1798, General Humbert proclaimed the establishment of a government for one of the provinces of the Irish Republic, Connacht. Humbert also selected John Moore as the President of the Government of the Province of Connacht. Nevertheless, as civil or political appointments were not made for any other province except Connacht, the Republic of Connacht is the name for the 1798 Irish Republic that has long been commonly used.

There was little effective government, given the state's brief and troubled existence. Whether it was ever recognised by France is unknown: the French supported the United Irish who aimed to establish an island-wide republic. Some of the principle events in the short-lived Republic were the following:

The Battle of Castlebar on 27 August 1798 at which the French and Irish forces defeated the British forces in the town of Castlebar;
The establishment of a Government of the Province of Connacht on 31 August 1798 with John Moore as its President;
The Battle of Ballinamuck on 8 September 1798 at which the French and Irish were effectively defeated and the French forces surrendered; and
The final defeat on 23 September 1798 when rebels in Killala, having made a last stand against General Trench and the British forces, were defeated.

Although achieving a spectacular victory at Castlebar, the losses of the French and Irish were high, losing about 150 men, mostly to the cannonade at the start of the battle. The British suffered over 350 casualties of which about 80 were killed, the rest either wounded or captured, including perhaps 150 who joined the rebels. Following the victory, thousands of volunteers flocked to join the French who also sent a request to France for reinforcements.

Ultimately defeated by Cornwallis at the Battle of Ballinamuck the republic ceased to exist and the Kingdom of Ireland was later absorbed into the United Kingdom of Great Britain and Ireland in 1801.

Though seemingly an anecdotal episode in modern Irish and British history, it was remembered locally as a landmark event and part of the heritage of "The Year of the French".