Late 15th Century onwards
In 1487 Iain Maclachlan of Strathlachlan, witnessed a bond by Dougall Stewart of Appin to Colin Campbell, 1st Earl of Argyll. Iain died sometime around 1509 and his son Gillescop (or alternately Archibald) married a daughter of Iain Lamont of Inveryne, the chief of Clan Lamont. Iain was succeeded by his son, Lachlan, who later on forcibly ejected Archibald Lamont of Stroiog from his lands. For this, the Maclachlan chief was summoned before the Privy Council, which ruled that even though Lachlan claimed Lamont lands through his maternal grandfather (the chief of Clan Lamont), that a Lamont heir was more preferable to a Maclachlan heir. Lachlan died sometime between 1557 and 1559, and was succeeded by his second son, Archibald. In 1587, the chief of the clan, "M'Lauchlane", appears on the roll of names of the landlords in the highlands and the isles, on whose land broken men dwelt. Archibald had only daughters and in turn was succeeded by his nephew Lachlan Og ("Lauchlane oig Macklauchlane his brothers sone").
Not long after assuming the chiefship, Lachlan Og was forced to resign some of his lands to the chief of the Lamonts, because of the murder of Robert Lamont of Silvercrags by Lachlan Maclachlan of Dunnamuch. Lachlan Og led the clan in the Archibald Campbell, 7th Earl of Argyll's campaign against Sir James Macdonald of Islay and his rebellion in 1615.
Lachlan Maclachlan of that Ilk was succeeded by his son Archibald, who is reckoned as the fifteenth chief of the clan. In 1680 Archibald had his lands erected into a Barony by Charles II of England called the Barony of Strathlachlan which was centred around Lachlan Castle.To this day the chief of the clan is styled as Baron of Strathlachlan.