After the fall of Drogheda in September 1649, the Marquis of Ormond retreated to Kilkenny with his remaining forces, abandoning the garrisons of Trim and Dundalk. With the losses sustained at Rathmines and Drogheda, Ormond was unable to muster an army strong enough to challenge Cromwell, which left the north-western approaches to Dublin secure for the Parliamentarians. While Colonel Venables advanced into Ulster, Oliver Cromwell planned to march rapidly south from Dublin to capture the main seaports of Leinster and Munster before the onset of winter, thus cutting the Royalists’ most direct line of communications with France and Spain.

Cromwell’s first objective was to capture Wexford, which was a potential port of entry for Royalist support from the Continent and was also a notorious base for privateering raids on English shipping. The Parliamentarians arrived before Wexford on 1 October 1649. Meanwhile, the Marquis of Ormond reinforced the Wexford garrison with 1,000 men under the command of Colonel David Synnot and moved his field army to New Ross in order to protect Wexford’s supply lines.

Wexford is situated on the south side of the mouth of the River Slaney. Its harbour is sheltered by two fingers of land to the north and south and was guarded by Rosslare Fort on the southern finger. Cromwell crossed the Slaney at Enniscorthy and approached Wexford from the south. The speed of his advance took the citizens of Wexford by surprise. The Rosslare garrison was unprepared for an attack by Lieutenant-General Michael Jones on 2 October and fled at the approach of his advance guard of dragoons. The capture of Rosslare allowed Cromwell’s support fleet to enter Wexford Bay in safety and unload the heavy siege artillery on the south side of the town. Cromwell set up his batteries to concentrate their fire on Wexford Castle which dominated the south-eastern corner of the defences and which overlooked part of the town wall.

Cromwell issued his summons to surrender on 3 October 1649, offering lenient terms in the hope that he could secure Wexford intact and use it as winter quarters for his troops. The mayor, aldermen and many citizens of Wexford were prepared to surrender but Colonel Synnott played for time, in accordance with Ormond’s strategy of waiting for disease and attrition to weaken the Parliamentarians while the Royalist-Confederate army was steadily rebuilt.

Negotiations between Cromwell and Synnot continued until 10 October when Cromwell’s patience ran out and he ordered his artillery to begin bombarding the walls of Wexford Castle. The following day, Synnot and the aldermen of Wexford agreed to accept Cromwell’s terms, by which the soldiers of the garrison would be disarmed and allowed to march away, the officers would become prisoners and the town would not be plundered. However, when a delegation from Wexford met Cromwell to finalise the surrender, a further set of proposals was presented to him for negotiation. These included provisions for the protection of the town’s Catholic clergy, a proposal that the garrison be allowed to withdraw to New Ross with all their weapons and ammunition and a proposal that the merchant privateers of Wexford could sail away with their goods and ships intact. These terms were unacceptable to Cromwell and negotiations broke down.

The Parliamentarian artillery continued to bombard Wexford Castle while the negotiations were in progress. On the afternoon of 11 October, the gunners succeeded in opening two wide breaches in the castle wall. With the breakdown of the main negotiations, Captain Stafford, the commander of the castle, agreed to surrender it before an assault was launched. When Cromwell’s troops appeared on the castle battlements and turned its guns on Wexford, the Royalists guarding the south wall of the town lost heart and fled. The Parliamentarians launched an immediate attack, scaling the abandoned walls, opening the gates and storming into the town. The Royalists made a stand in the market square, but they were quickly overwhelmed. Cromwell and his officers made no attempt to restrain their soldiers, who slaughtered the defenders of Wexford and plundered the town. Colonel Synott was among those killed. Hundreds of civilians were shot or drowned as they tried to escape the carnage by fleeing across the River Slaney.

Angered at Synott’s last-minute attempt to change the terms of surrender, Cromwell expressed no remorse for the massacre of civilians at Wexford in his subsequent report to Parliament. He regarded it as a further judgment upon the perpetrators of the Catholic uprising of 1641 and also upon the pirates who had operated out of Wexford harbour. His principal regret was that the town was so badly damaged during the sack that it was no longer suitable as winter quarters for the Parliamentarian army.

The loss of Wexford was another major blow to the Royalist-Confederate coalition. For the loss of only twenty or thirty Parliamentarians, around 2,000 Royalist soldiers were killed or dispersed, reducing Ormond’s field army to less than 3,000 men. The Parliamentarians captured ships, artillery, ammunition and tons of supplies. Wexford harbour provided the Parliamentarians with a naval base in southern Ireland where further supplies from southern England could be received. The Irish privateering fleet was broken up, leaving Prince Rupert’s ineffective squadron at Kinsale as the only potential threat to Commonwealth shipping and Cromwell’s supply lines. Shortly after the fall of Wexford, Rupert broke out of Kinsale and escaped to Portugal.