From the National Trust for Scotland web site:
On 19 August 1745, at the head of Loch Shiel, Prince Charles Edward Stuart raised his Standard,
marking the start of his campaign to restore the exiled Stuarts to the throne. From this spot,
Bonnie Prince Charlie and his followers made it as far south as Derby before their eventual defeat
the following year at Culloden. The Glenfinnan Monument was designed by the Scottish architect
James Gillespie Graham, and was erected in 1815 by Alexander Macdonald of Glenaladale as a tribute
to the clansmen who fought and died in the cause of the Stuarts.