Arthur’s 2nd, 3rd 4th & 5th battles were fought at the River Douglas and there are many rivers in Scotland of this name, however the one we are looking for is in the region of the Linnius. Skene equates the Linnius with the Lennox, the ancient Scottish Earldom which lies to the north of the River Clyde, to the west of the River Kelvin, to the south of the Campsie Fells (the Kingdom of Bannog) and stretches to the north end of Loch Lomond including the strip of land between Loch Lomond and Loch Long (formerly known as The Isle). It is on The Isle high above the west bank of Loch Lomond (or The Lake) that we find Glen Douglas, a site of many ferocious clan battles and atrocities which still holds a high military presence today.
Glen Douglas (O.S. Map Ref. NS 304 990) lies about 15 miles north of Dumbarton Rock (the all important Fortress of the Britons) and just across Loch Long from Ben Arthur and Arthur’s Seat. The Glen is still well within the bounds of the old British Kingdom of Strathclyde and close to the western extremity of the 6th century expansionary Scottish Kingdom of Dalriada where Artur MacAeden’s Pendragon father took the throne in 574.
There was no road on The Bonnie Banks until the middle of the 19th century and everything had to be moved by boat. This suggests that these battles would have been naval supported encounters drawing forces from Dumbarton at the other end of The Lake. There is an old route from Arrochar to Luss called the String Road which passes through the hills and crosses Glen Douglas. This is the reason why so many later cattle raids and clan clashes occurred here - Perhaps Arthur was fighting for similar reasons, but who with? Raiding Picts from the north, raiding Scots from the west, a seaborne raid from the south or all three? I doubt we will ever know unless someone gets digging!
A second option for the location of the River Dubglas is the Douglas Water in Clydesdale (O.S. Map Ref. NS 835 305). This site should not be lightly discarded as it still lies well within the sphere of 6th century North British influence and close to the tribal region occupied by the Borders Selgovae who we shall meet in due course at Ardrydd.