Donal Cam O'Sullivan Beare, Prince of Beare, 1st Count of Berehaven (Irish: Domhnall Cam Ó Súileabháin Bhéara) (1561–1618), was the last independent ruler of the O'Sullivan Beara sept, and thus the last O'Sullivan Beare, a Gaelic princely title, on the Beara Peninsula in the southwest of Ireland during the early seventeenth century, when the English Crown was attempting to secure their rule over the whole island.
Donal himself was absent from the siege of Dunboy, having travelled to Ulster for a conference with Lord Tyrone. His letter to Philip left him with little hope of a pardon from the English, and he continued the fight with guerilla tactics.
He concealed 300 of the women, children and aged of his community in a stronghold on Dursey Island, but this position was attacked, and the defenders hanged. In what was later termed the Dursey Massacre, Philip O'Sullivan Beare (c.1590-1660; nephew of Donal Cam O'Sullivan Beare) wrote that the women and children of the Dursey stronghold were massacred by the English, who tied them back-to-back, threw them from the cliffs, and shot at them with muskets.
After the fall of Dursey and Dunboy, O'Sullivan Beare, Lord of Beara and Bantry, gathered his remaining followers and set off northwards on a 500-kilometre march with 1,000 of his remaining people, starting on 31 December 1602. He hoped to meet Lord Tyrone on the shores of Lough Neagh.
He fought a long rearguard action northwards through Ireland, through Munster, Connacht and Ulster, during which the much larger English force and their Irish allies fought him all the way. The march was marked by the suffering of the fleeing and starving O'Sullivans as they sought food from an already decimated Irish countryside in winter. They faced equally desperate people in this, often resulting in hostility, such as from the Mac Egans at Redwood Castle in Tipperary and at Donohill in O'Dwyer's country, where they raided the food store of The 10th Earl of Ormond. O'Sullivan marched through Aughrim, where he raided villages for food and met local resistance. He was barred entrance to Glinsk Castle and led his refugees further north. On their arrival at The O'Rourke's castle in West Breifne on 4 January 1603, after a fortnight's hard marching and fighting, only 35 of the original 1,000 remained. Many had died in battles or from exposure and hunger, and others had taken shelter or fled along the route. O'Sullivan Beare had marched over 500 kilometres, crossed the River Shannon in the dark of a midwinter night (having taken just two days to make a boat of skin and hazel rods to carry 28 at a time the half-kilometre across the river), fought battles and constant skirmishes, and lost almost all of his people during the hardships of the journey.
In County Leitrim, O'Sullivan Beare sought to join with other northern chiefs to fight the English, and organised a force to this end, but resistance ended when Lord Tyrone signed the Treaty of Mellifont. O'Sullivan, like other members of the Gaelic nobility of Ireland who fled, sought exile, making his escape to Spain by ship.
The Beara-Breifne Way long-distance walking trail follows closely the line of the historical march.