The MacFarlanes claim descent from the Earls of Lennox, citing Gilchrist, the younger brother of Malduin, both sons of Alwyn, the 3rd Earl, as their ancestor. The clan was famous for its warlike behaviour. Gilchrist's grandson was one of the Gaelic supporters of Robert the Bruce, and father of Parlan (a P-Celtic name). Its Gaelic form was 'Farlan' , hence MacFarlane.
Iain MacPharlain, the 7th Chief, to descend from Gilchrist, received a confirmation of his title to Arrochar in 1420, and Earl Duncan of Lennox was beheaded by James I in a particularly revolting way, the House of MacFarlane became the senior male representatives of he ancient Earldom of Lennox, although this was later taken by the Stewarts.
The MacFarlanes remained loyal to the Stewarts, and in particular to their Lennox branch. Sir Iain, the 11th Chief fell in the Lennox contingent at Flodden in 1513, leaving as his heir, Andrew. Duncan, the 13th Chief, fell fighting the English at Pinkie in 1547, during the short reign of Mary. His men had been described as being at the head of the Lennox, that spoke Gaelic and Scottish.
After the death of Mary's husband, King Henry (Lord Darnley), his father, the Earl of Lennox sided with Mary's enemies. The 14th Chief of he MacFarlanes took a contingent of troops to Loch Leven castle which tipped the scales against her. Sadly, the MacFarlanes were notorious for feuds with the Colquhouns and the Buchanans. As a result, the MacFarlane name and lands were forfeited in 1642, and its clan members were dispersed (similar to the MacGregors).
However, the clan returned to its Royal loyalties when the 16th Chief fought under Montrose for Charles I. His island stronghold of Inveruglas in Loch Lomond was destroyed by the Roundheads when Cromwell invaded Scotland. Thereafter, the seat of the MacFarlanes became the house of Arrochar by Loch Long.
The 20th Chief set a remarkable example. Walter MacFarlane devoted his entire life to research into the history of his country, and the preservation and transcribing of its documents. His accurate and thorough collections have proven to be invaluable. Soon after this excellent Chief's death in 1767 without heirs, his brother sold Arrochar. The direct male line of chiefs expired with the death of William, the 25th Chief, in 1886, without issue.