Elizabeth Fort was one of several such forts constructed around Cork during the late 16th and 17th centuries. Bastioned forts were built in Cork Harbour at Carlisle Fort and on Haulbowline Island. Charles Fort and James Fort guarded the entrance to Kinsale Harbour. These new defences indicated Cork’s growing importance as a centre of maritime trade and commerce.
The defences were tested in the middle of the 17th century. Cork was the scene of further military unrest in 1649. The previous eight years had seen brutal civil warfare across Britain and Ireland between Irish, Royalist and Parliamentary forces. Oliver Cromwell came to Ireland in August to crush any remaining resistance to his Parliamentary army. His bloody conquest of several Irish towns spread fear before him, so it is unsurprising that the citizens of Cork surrendered with little resistance. It is said that Cromwell ordered improvements to Elizabeth Fort, and that the walls were increased in height by over 4 metres at the time. Local folklore says that one of the many biting insects that lived in the marshy surrounding land bit Cromwell, infecting him with the suspected malaria that so afflicted his later life and eventually led to his death. He complained of having contracted ‘Cork Fever’ in a letter to his wife. Although the city may have surrendered without a fight, Cork left its mark on Cromwell.
The 17th century was one of the most turbulent, violent and chaotic eras in Irish history. In the 1690s, the Williamite Wars raged across the land. Following the defeat of the Jacobites at the Battle of the Boyne in July 1690, their forces retreated to the south and west of Ireland. They took control of Cork, but in September, 5,000 Williamite soldiers arrived by ship to lay siege to the city. They came ashore at Passage West about six miles south-east of Cork and were joined from the north by reinforcements of another 5,000 men. The siege exposed the defensive weaknesses of Elizabeth Fort. Although it dominated the city, the fort itself was exposed to the south and east. A smaller fortification known as the Catt Fort guarded the high ground to the south-east of Elizabeth Fort. This small fort was quickly taken by the Williamites after the Jacobite soldiers abandoned it. From this vantage point the Williamites bombarded Elizabeth Fort with cannon fire, inflicting considerable damage on the south wall and the gateway. While the fort was under bombardment, Williamite snipers climbed the bell tower of a church that stood where St. Fin Barre’s Cathedral stands today. The tower overlooked the north-west bastion of the fort. From this position, the sharpshooters were able to lay down murderous fire into the fort, and they succeeded in killing the Jacobite commander of the fort, Lieutenant-Colonel Bousquet.
In response, the Jacobites aimed their cannons at the church tower and opened fire. A cannonball fired during the siege was discovered when the new St Fin Barre’s Cathedral was being built and it is still on display inside the cathedral. The siege of Cork lasted about five days. It came to a conclusion when the Williamites brought artillery up the river and began firing at the eastern walls of the city. When they breached the walls and prepared to storm the city, the Jacobites decided to surrender. The terms of surrender of the city of Cork included that Elizabeth Fort would also be surrendered, despite the fact that the fort had withstood the siege. When the Williamite General Scravemoer entered the fort afterwards, he is quoted as saying that Elizabeth Fort “on my word is almost impregnable”.