From the 17th to the 19th century it was part of the large estate belonging to the Temple family in north Sligo. The land, some 12,000 acres, was granted to Sir John Temple, 1st Viscount Palmerston and Master of the Rolls in Dublin. The 3rd Viscount, Henry John Temple, better known as Lord Palmerston, began the building of the castle of Classiebawn, a baronial style house standing on the peninsula. He also built the stone-walled harbour in the village, which was designed by the marine engineer Alexander Nimmo. It was built between 1822 and 1841.
The Temples were mostly absentee landlords, with the estate being run initially by middlemen, and later by land agents, such as Stewart and Kincaid, a Dublin firm with offices in Sligo. These agents, in their attempts to make the estates profitable, oversaw the “assisted emigration” that took place on the Palmerston and adjacent Gore Booth (Lissadell) estate that began before the famine and continued until at least the 1860s.
Thus, in May 1862, a Sligo newspaper reported: “In accordance with a custom of some years standing, about sixty persons have been selected for emigration from the Parish of Ahamlish … whose passages and outfit has been provided by his Lordship. They consist of twenty-four young girls, and twenty young men … [and] families who were wholly unable to support themselves … who had asked the favour of being sent out ….. The emigrants took their passages … this day, for Liverpool, en route for America.”
Lord Palmerston presided over Mullaghmore and North Sligo during the worst years of the Irish Holocaust, the great famine of the mid 19th century. During the summer and autumn of 1847, nine vessels, carrying over 2,000 persons left Sligo port with tenants evicted and “shovelled out” from his Sligo estates. They arrived in Canada half naked and totally destitute. The city of St. John in the Canadian province of New Brunswick had to take many of Palmerston’s evicted tenants into care and, outraged, sent a scathing letter to Palmerston expressing regret and fury that he or his agents, ‘should have exposed such a numerous and distressed portion of his tenantry to the severity and privation of a New Brunswick winter ……unprovided with the common means of support, with broken down constitutions and almost in a state of nudity ….. without regard to humanity or even common decency.’ The graves of many of these unfortunate victims can be seen today on the old quarantine station, now a museum, at Grosse Ille near Quebec .
Classiebawn was a favoured holiday retreat of Admiral of the Fleet Louis Mountbatten, 1st Earl Mountbatten of Burma, the last Viceroy of India, who had inherited Classiebawn Castle. It was off the Mullaghmore coast in August 1979 that Lord Mountbatten, along with The Dowager Baroness Brabourne and County Fermanagh teenager Paul Maxwell, were killed by a bomb planted by the Provisional IRA.
In 2007 it hosted the final stage of Rally Ireland.