Siege of Limerick ( 1650 – 51 ) Limerick , in western Ireland was the scene of two sieges during the Irish Confederate Wars . The second and largest of these took place during the Cromwellian conquest of Ireland in 1650 – 51 . Limerick was one the last fortified cities held by an alliance of Irish Confederate Catholics and English Royalists against the forces of the English Parliament . Its garrison , led by Hugh Dubh O ' Neill , surrendered to Henry Ireton after a protracted and bitter siege . Over 2 , 000 soldiers of Cromwell ' s New Model Army were killed at Limerick , and Henry Ireton , Cromwell ' s son - in - law died of Plague . Ireton ' s first siege , October 1650 . By 1650 , The Irish Confederates and their English Royalist allies had been driven out of eastern Ireland by the Cromwellian conquest of Ireland . They occupied a defensive position behind the River Shannon , of which Limerick was the southern stronghold . Oliver Cromwell himself had left Ireland in May 1650 , delegating his command of the English Parliamentarian forces to Henry Ireton . Ireton moved his forces north from Munster to besiege Limerick in October of that year . However , the weather was increasingly wet and cold and Ireton was forced to abandon the siege before the onset of winter . June 1651 , Ireton returns – Limerick blockaded . Ireton returned the following June with 8 , 000 men , 28 siege artillery pieces and 4 mortars . He then summoned Hugh Dubh O ' Neill , the Irish commander of Limerick to surrender , but was refused . The siege was on . Limerick in 1651 was split into two sections , English town and Irish town , which were separated by the Abbey River . English town , which contained the citadel of King John ’ s Castle , was encircled by water , the Abbey river on three sides and the Shannon on the other , in what was known as King ' s Island . There was only one bridge onto the island – Thomond bridge – which was fortified with bastioned earthworks . Irish town was more vulnerable , but was also more heavily fortified . Its medieval walls had been buttressed by 20 feet ( about 6 metres ) of earth , making it difficult to knock a breach in them . In addition , Irish town had a series of bastions along its walls , mounted with cannon which covered its approaches . The biggest of these bastions were at St John ’ s Gate and Mungret gate . The garrison of the city was 2 , 000 strong and composed mainly of veterans from the Confederate ’ s Ulster army , commanded by Hugh Dubh O ' Neill , who had distinguished themselves at the siege of Clonmel the previous year . Because Limerick was very well fortified , Ireton did not risk an assault on its walls . Instead he secured the approaches to the city , cut off its supplies and built artillery earthworks to bombard the defenders . His troops took the fort at Thomond bridge , but the Irish destroyed the bridge itself , denying the Parliamentarians land access to English town . Ireton then tried an amphibious attack on the city , a storming party attacking the city in small boats . They were initially successful , but O ’ Neill ’ s men counterattacked and beat them off . After this attack failed , Ireton resolved to starve the city into submission and built two forts known as Ireton ’ s fort and Cromwell ’ s fort on nearby Singland Hill . An Irish attempt to relieve the city from the south was routed at the battle of Knocknaclashy . O ’ Neill ’ s only hope was now to hold out until bad weather and hunger forced Ireton to raise the siege . To this end , O ’ Neill tried to send the town ’ s old men , women and children out of the city so that his supplies would last a little longer . However , Ireton ’ s men killed 40 of these civilians and sent the rest back into Limerick . The surrender , October 1651 . After this point , O ’ Neill came under pressure from the town ’ s mayor and civilian population to surrender . The town ’ s garrison and civilians suffered terribly from hunger and disease , especially an outbreak of plague . What was more , Ireton found a weak point in the defences of Irish town , and knocked a breach in them , opening the prospect of an all out assault . Eventually in October 1651 , six months after the siege had started , part of Limerick ’ s garrison ( English Royalists under Colonel Fennell ) mutinied and turned some cannon inwards , threatening to fire on O ’ Neill ’ s men unless they surrendered . Hugh Dubh O ’ Neill surrendered Limerick on 27 October . The inhabitants lives and property were respected , but they were warned that they could be evicted in the future . The garrison was allowed to march to Galway , which was still holding out , but had to leave their weapons behind . However , the lives of the civilian and military leaders of Limerick were excepted from the terms of surrender . A Catholic Bishop Terence Albert O ' Brien , an Alderman and the English Royalist officer Colonel Fennell ( who the Parliamentarians said was a " soldier of fortune " ) were hanged . O ’ Neill was also sentenced to death , but was reprieved by the Parliamentarian commander Edmund Ludlow and imprisoned instead in London . Former mayor Dominic Fanning was drawn , quartered , and decapitated , with his head mounted over St . John ' s Gate . The cost . Over 2 , 000 English Parliamentary soldiers died at Limerick , mostly from disease . Among them was Henry Ireton , who died a month after the fall of the city . About 700 of the Irish garrison died and an unknown , but probably far greater number of civilians – usually estimated at about 5 , 000 . Sources . city