On the east side of Loch Sween, this castle guards the mouth of the Loch, looking past nearby islands and down the Sound of Jura towards Ireland. It is one of the earliest stone castles in western Scotland, having been built towards the end of the 1100s.
Its plan is that of a quadrangle, with projecting buttresses, an unusual feature in a western highland fortification. The gateway is on the south side, in a ten foot thick section of masonry. There is a well in the north east angle. MacMillan's Tower, of later, 15th century date, is outside the north east angle. The round tower at the north west angle contained a prison at one time.
Its situation would have made it convenient to beach galleys, there being no natural anchorage nearby. The early history and siting of this castle have much to do with the emphasis upon sea power which dominated western Argyll.until Scotland looked to Edinburgh and London for its law and order.
A leader named "Suibhne" (grandson of Hugh the Splendid who died 1047 AD), is credited with building Castle Sween. By the 13th Century, the Clan MacSween lands extended as far as Lochawe in the north and Skipness Castle on Loch Fyne in the South. The family was, however, on the wrong side of the Wars of Independence in the early 1300s. When Robert the Bruce became King of Scotland, he displaced the MacSweens, and granted the Castle to his loyal supporter, Angus (Macdonald) of Islay. The MacSweens made at least one attempt to reclaim their ancient property, as immortalized in a poem found in the Dean of Lismore's Book.* Eventually, with the fall of the MacDonald sea power, the Castle ended up in the hands of the Campbells (1490).
Throughout, the Constables of Castle Sween seem to have continued to be the MacNeills. The last MacNeill to hold this position was Hector Torquil MacNeill, 1st of Taynish. When he died, his wife, Effric McCorquadale, wrote a lament, also to be found in the Dean of Lismore's Book.*
This Hector MacNeill's only lawful descendent was his daughter, Erca. When she married Alexander MacMillan, her dowry consisted 10 farms extending from the Castle to the head of Loch Caolisport to the east. She and her husband lived at the Castle, and it was for them that 'MacMillan's Tower' was built. The Constableship of the Castle thus passed to the MacMillans. This clan retained its prominence in Knapdale into the 1900s. One branch played a central role in the Arichonan Affray of 1848.
During the British Civil War, Castle Sween was attacked and burned in 1644 by Alisdair MacColla and his Clan Donald, during his ravaging of the clan Campbell's Argyll. The Castle has been a ruin ever since.
*DEAN OF LISMORE'S BOOK
This is a compilation of Gaelic poetic work combiled between 1512 and 1526, chiefly by Sir James McGregor, the Dean of Lismore, and his brother Duncan. The original (at the National Library of Scotland) is a small quarto about 7 inches square, and a little over 1 inch in thickness, and bound with a piece of coarse sheepskin. You can now download a copy of the translation made in 1862 by the Rev. Thomas McLauchlan with an introduction by Wm F Skene in 1862 from Google Books!