The Siege of Clonmel took place in April - May 1650 during the Cromwellian conquest of Ireland when the town of Clonmel in County Tipperary was besieged by Oliver Cromwell's New Model Army. Cromwell's 8,000 men eventually took the town from its 2,000 Irish defenders, but not before they suffered losses of around 2,000 soldiers. Most were killed after being caught in a trap by Hugh Dubh ("Black Hugh") O'Neill on 17 May 1650.

Prelude:

The garrison at Clonmel changed as the arrival of the Puritan army through Kilkenny became imminent. In November, 1649, the town's Mayor John Bennet White wrote to the Duke of Ormond seeking military assistance. Colonel Oliver Stephenson and part of the old Confederate army, mostly from County Clare, took up quarters. The southern Confederates were not fully trusted by the townspeople, particularly after the fall of Carrick on Suir due to treachery. Ormond arrived in person at the end of the month and the Clare men were replaced by experienced soldiers from Ulster under Hugh Dubh ("Black Hugh") O'Neill, a veteran of siege warfare in the Thirty Years' War. Under his command were 1,500 soldiers from the Irish Ulster army, mostly from the modern counties of Tyrone and Cavan. These two regiments had served under Owen Roe O'Neill and were now led by his nephew. They were accompanied by two troops of cavalry under Colonel Edmond Fennell of Ballygriffin, Co. Cork. O'Neill sent reinforcements to some outlying fortifications at Ballydine, Kilcash and 'Castle Caonagh' (Mountain Castle). Even before the siege commenced, provisioning the new influx was causing difficulties, Ormond proving unable to adequately supply them. As other walled towns in the vicinity capitulated with little resistance, tension in the town rose as evidenced by correspondence between O'Neill and Ormond.

May it please your Excellencie.

This day I received your letter of the 25th of this instant [February]. Since my last letter to your Excie. I have not to intimate more than that Cahir was yielded without shot or blowe upon what conditions I knowe not, which I believe your Excie knows ere nowe, likewise Kilteenan was beseedged eare yesternight and yielded yesterdaye morninge about nyne of the clocke. All their armye is within a myle to the towne, and the rest are cominge to them, in great hast they have sent a number of horse and oxen for more cannons. Wee expect nothinge else but bee besieged every houre they having nowe noe other place to ayme at but this. Your Excie may knowe in what condicon wee are and the consequence of this place to the Kingdom which requires a speedy succour all which I humbly referre to your Lordshipps grave consideratacon I humbly take leave and remayne
Your Excies most humble servt, Hugo O'Neill Clonmell ultimo [28th] February

to which Ormond responded in the following terms :

Sir - Your letter of the last of February intimating your expectation of suddainly besieged I received not till about nine of the clock this morning. In answeare whereunto I thinke fitt to assure you by these that rather then that towne should fall into the hands of the rebels I shall draw all the forces of the Kingdome into a body for its reliefe which I shall endeavour soe to effect as in ten dayes to be in a readiness to advance to towards you, relying on your uttermost endeavours to defend that place during that tyme though you should as you expect be closely besieged and soe deseiring to heare as frequently from you as possibly you may. I remaine Your very affectionate friend, Ormond. Ennis 5 March about 12 in the forenoone

Cromwell was in a hurry to take the town as he had been summoned back to England by the English Parliament to deal with a Royalist uprising there. As a result he tried to take Clonmel immediately by assault, rather than opt for a lengthy siege.

The assault:

Cromwell's artillery, positioned on a hill near present-day Melview, battered a breach in the town walls. It was intended that his infantry would storm this breech and then open the nearby North town gate to allow access to Cromwell and the Parliamentarian cavalry.

However, O'Neill put all able bodied townspeople to work building a coupure inside the breach lined with artillery, muskets and pikemen. The coupure was v-shaped, starting at the mouth of the breach and narrowing until it ended about 50 metres inside the town. At the end of the breach, O'Neill positioned two cannon, loaded with chain-shot. The area behind the breach became, in military terms, a "killing field". The Parliamentarian infantry which assaulted the breach was repeatedly cut down by the concentrated musket and cannon fire until the soldiers finally refused to make any further attacks on what was a death trap. Cromwell then appealed to his elite cavalry, the Ironsides to make a fresh assault on foot. They assaulted the breach for three hours, taking heavy casualties but failing to break into the town. Eventually, as night fell, Cromwell called off the assault.

Town surrenders:

However, O'Neill's men were out of ammunition and slipped away under cover of darkness - making their way to Waterford. Cromwell negotiated a surrender with the town's mayor, John White, believing that Clonmel was still heavily defended. The surrender terms stipulated that the lives and property of the townspeople would be respected. Cromwell, although angry at the deception, did not allow his soldiers to abuse the terms of the surrender when he found that the garrison was gone and the town defenceless. His admirers cite this as an example of his integrity while his critics contrast it with the massacre he ordered at Drogheda the previous year.

Aftermath:

The New Model Army lost at least 1500 men killed at Clonmel, and possibly as many as 2500, with hundreds more wounded, its largest ever loss in a single day.