Siege of Duncannon The Siege of Duncannon took place in 1645 , during the Irish Confederate Wars . An Irish Catholic Confederate army under Thomas Preston besieged and successfully took the town of Duncannon in south eastern Ireland from its English Parliamentarian garrison . The siege was the first conflict in Ireland in which mortars were employed . Background . At the outbreak of the Irish Rebellion of 1641 , most of south - eastern Ireland fell to the Catholic insurgents . Roughly 1 , 000 rebels blockaded Duncannon , which was heavily fortified and contained an English garrison of about 300 men . Around 150 of the English troops were killed in forays against the Irish at nearby Redmond ' s Hall , but without siege artillery , or expertise in siege warfare , the rebels were unable to take Duncannon . Hostilities continued throughout 1642 , as the Irish , now organised as the Confederate Catholics of Ireland raided the town ' s hinterland . As in much of Ireland , the conflict was bitter . In one incident , Laurence Esmonde , Lord Esmonde , the Royalist commander hung 16 Irish prisoners who had been taken at nearby Ramsgrange . In response , the Irish executed 18 English prisoners whom they had been holding . In 1643 , because of his need for troops to fight in the English Civil War , Charles I signed a ceasefire with the Irish Confederates . As a result hostilities between Duncannon and the Catholic held surrounding area were suspended . Esmond Changes sides . However , in 1644 , the English garrison of Cork , under Lord Inchiquin , unhappy with the Royalist truce with the Irish Confederates , declared for the English Parliament , who were to remain hostile to Irish Catholic forces throughout the 1640s . Esmond , under pressure from elements of his garrison , also changed to the side of Parliament and effectively re - declared war on the Catholic Confederates . His motives are not entirely clear : though he was a Protestant convert , the Esmonde family were Anglo - Irish Catholics , and he owed his entire advancement to the Crown . Duncannon was a strategically important town for two reasons . Firstly , it had formidable defences . Secondly and more importantly , its guns overlooked the sea route to Waterford and New Ross , two of the most important Catholic held towns and also ports at which the Confederates received military aid from Catholic Europe . Needing to keep this channel open and also fearing the presence of an English garrison deep in their territory , the Confederates ' Supreme Council in Kilkenny despatched Thomas Preston , general of their Leinster Army , to take Duncannon in January 1645 . Preston had at his disposal 1 , 300 men , four cannon and a mortar . The mortar , the first of its kind to be used in Ireland had been donated by Spain the previous year and was commanded by a French military engineer named Nicholas La Loue . La Loue had served with Preston in Flanders and was chief of engineering in the Leinster Army . The Siege . Duncannon possessed formidable defences . For one thing , it was located on a peninsula and could only be approached from the north , the other three sides jutting out into the sea . Just off the town were docked four Parliamentarian ships , which were supplying Duncannon with food and reinforcements . Secondly , it possessed two lines of fortifications , the outer line being a more modern low deep rampart protected by a dry ditch and the inner wall being a medieval curtain wall , complete with three towers . However , it had two grave weaknesses , first , it was overlooked by a hill to the north , from which an attacker could fire into the town and secondly the water supply was also located outside the walls . Preston arrived at Duncannon on January 20 and proceeded to construct a ring of trenches which cut off Duncannon on its landward side . From the hill that overlooked the town to the north , his guns were able to fire on a squadron of four Parliamentarian ships that were docked off Duncannon and providing the town with supplies . The Flagship , the " Great Louis " was badly damaged , its mast wrecked by cannon fire , and it took several more hits from the mortar as it tried to get away . The ship sunk in deep water , drowning its crew and 200 soldiers who had been on board . Having cut off Duncannon ' s supply from the sea , Preston proceeded to dig saps closer to the walls , the ultimate aim being to bring his cannon close enough to the walls in order to blast a breach and open the way for an assault . His engineers also dug a mine underneath one of the town ' s bastions . All the while , the town ' s defenders were kept under a bombardment by the mortar and , as the Confederate troops got closer to the walls , by sharpshooter s . On March 12 , one such sniper killed the fort ' s second in command , one Captain Lurcan , who was hit in the head by a bullet . On March 16 , by which time the Irish trenches were , ' within pistol shot of the walls ' , Preston ordered the mine to be exploded , opening a breach in Duncannon ' s outer walls . The Irish infantry then assaulted the town , but were beaten off with some losses . The following day , St Patricks Day , Preston tried again and this time his troops succeeded taking the town ' s outer , more modern walls but were stopped at Duncannon ' s inner , medieval ramparts . They had succeeded in occupying one of the town ' s towers for an hour before being beaten back . Geoffrey Barron , a Confederate politician , who kept a diary of the siege , reported that 24 Irish soldiers were killed in the two assaults . The Surrender . At this point , Preston summoned Esmond to surrender , before he had to , ' proceed to extremities ' . This was a delicate threat , implying that if the town fell to an assault , its defenders would be put to the sword - as was customary in contemporary siege warfare . Esmond was also advised to surrender by the Parliamentarian vice admiral , William Smith , who was anchored off shore with seven ships , but could not break through to relieve the town . In a letter that reached Esmond on March 11 , Smith had warned him that , ' if the rebels take the fort by storming it , they will undoubtedley put you all to death . . . you should agree with thy adversary while thou art in the way ' . Esmond had Smith ' s letter publicly read to his troops after the assaults of March 16 – 17 to discourage those who favoured holding out . Alongside the risk of massacre , the English garrison was also very low on gunpowder and water . The town ' s only source of fresh water , a well , was behind the Confederate siege lines . In light of these facts , Esmond formally surrendered Duncannon to Preston on March 18 . The Confederates took possession of the town but its garrison was allowed to march away to Youghal , which was in Protestant hands . However , they had to leave behind the town ' s 18 artillery pieces . Esmond himself died a few days after the end of the siege . Preston would go on to briefly besiege Youghal , but bad weather , a lack of supplies and squabbling with Castlehaven , the Confederate Munster general , put an end to his campaign for that winter . The siege was of importance in that it re - opened the sea route into Waterford and eliminated a hostile English garrison in Confederate territory . Preston , who had for many years been the Spanish military governor of Leuven was highly experienced in siege warfare and his conduct of the siege drew widespread praise . Not only did he take the town , but he did so at a relatively low cost . Sixty seven Confederate soldiers died in the siege , of whom roughly 30 died of disease . Given that the campaign was conducted in mid - winter , in an age when disease routinely killed many more soldiers than combat , this represented a considerable logistical achievement on the part of the Irish general . The " Great Lewis " , the Parliamentarian ship sunk during the siege , was re - discovered in 1999 and raised in 2004 . The Cromwellian siege . Duncannon was besieged again during the Cromwellian conquest of Ireland by the forces of the English Parliament , as part of the Siege of Waterford . It repelled a siege by Oliver Cromwell in 1649 but surrendered after a lengthy blockade by Henry Ireton in 1650 .