When in Scotland

The legend is that in 1263 King Hakon of Norway sent an invasion fleet to Scotland in response to King Alexander III of Scotland wanting to buy the Western Isles and Kintyre from Norway. Legend has it that at some point during the invasion the Norsemen tried to surprise the sleeping Scots at Largs. 
In order to move more stealthily under the cover of darkness, the Norsemen removed their footwear. However as they crept barefoot, they came across an area of ground covered in thistles and one of Haakon’s men unfortunately stood on one and shrieked out in pain, thus alerting the Clansmen to the advancing Norsemen.
From henceforth the thistle has been one of Scotland's emblems.