Timucuan Indians began living on Cumberland about 4,000 years ago.
The Spanish arrived in the 1560s to establish missions, and stayed for about 100 years. The British next arrived, building forts in the 1700’s.
In 1786, Revolutionary War hero Nathanael Green and his wife Catharine were granted land on the island. Nathanael died shortly after, and Catharine and her second husband Phineas Miller build a home on the southern end that they named Dungeness.
In 1881, Thomas Carnegie – brother of steel magnate Andrew Carnegie – purchased land with his wife Lucy. They build a grand mansion on the site of the ruins of Green/Miller home and plantation, also naming it Dungeness. When Thomas died in 1886, Lucy continued to live there with their nine children. She built Plum Orchard as a wedding gift for her son George and his wife. When Lucy died in 1916, the Carnegie family owned most the island, and her will stipulated that no land could be sold until the last of her children died. Dungeness burned down in 1959, and the Carnegie heirs donated their land to the National Park Foundation in 1971.
The Spanish, British, and plantation owners all brought horses to Cumberland. During the Carnegie era, additional horses were released, joining existing free-ranging feral herds.