A Chief of the Colquhouns was issued a command by the King to seize the well-fortified Dumbarton Castle. He wrote the King back in French, the accepted universal language of the time, "Si Je Puis" (If I Can). The Chief gathered a group of men close to him and hid them in the woods outside of Dumbarton's gates. Then he lured a red stag (deer) by the gates chased by two greyhounds. The starving garrison in the castle opened the gates to chase the stag, whereupon the chiefs clansmen rushed the castle and captured it for the King. One of the most unusual details passed down with this story is that the Chief captured the castle without killing anyone which is remarkable not only for that time but for now, as well. The tour book that used to be passed out at Rossdhu states that the Chief could have been John Colquhoun 10th of Luss and the King, James I, who did choose Sir John to wrest the castle from the "too powerful" Lennox family in 1424.

Other sources say it could be Sir Robert 2nd de Colquhoun (1220-1280 AD) who apparently was the first to take the Colquhoun name (his father was the first Chief, Umfridus de Kilpatrick de Colquhoun).

Whatever the source of their name the Colquhouns have had a long, interesting and sometimes violent history. This Clan may well derive from a Norman immigrant family, or even earlier from a succession of Celtic Priests who were the custodians of the Crozier of St Kessog and who had lived on Monks Island on the loch. The name Colquhoun comes from the territory of that name situated to west of Loch Lomond.

1214 - 1249 Scots King Alexander II During this reign the head of the family - Humphrey De Colquhoun was granted the lands on the west of the loch by Malcom Earl of Lennox. This was confirmed by King Robert the Bruce for the Clan's support in the War of Independence

1368 Sir Robert Colquhoun married the fair Maid of Luss, heiress to nearby lands in Glen Luss and since then the clan name has properly been - Colquhoun of Luss

The Colquhouns supported King Robert the Bruce and backed the early Stewart Kings. In 1602 the Macgregors raided the Colquhouns in Glen Luss killing 2 clansmen, injuring others and carrying off hundreds of livestock.

Around the same time and after a conference between the two clans The Colquhouns hoped to trap the Macgregors in Glen Fruin, but there Intention was anticipated by Alistair Macgregor of Glenstrae, and after a bloody conflict the Colquhouns were defeated and their chief killed. In revenge they made a dramatic representation to the king (James VI) and the clan Macgregor was proscribed and their name forbidden under pain of death.