The song 'Flower of Scotland' celebrates Robert the Bruce's victory over which English king?

Roy Murdoch Buchanan Williamson (25 June 1936 – 12 August 1990) was a Scottish songwriter and folk musician, most notably with The Corries. Williamson is best known for writing "Flower of Scotland", which is used frequently at special occasions and sporting events. Although there is no official national anthem of Scotland, Flower of Scotland is one of a number of songs which fulfil this role, along with the older Scots Wha Hae, and Scotland the Brave, amongst others. It was written by Roy Williamson of the folk group the Corries, and presented in 1967, and refers to the victory of the Scots, led by Robert the Bruce, over England's Edward II at the Battle of Bannockburn in 1314.

The Battle of Bannockburn (24 June 1314) was a significant Scottish victory in the First War of Scottish Independence, and a landmark in Scottish history. Stirling Castle, a Scots royal fortress, occupied by the English, was under siege by the Scottish army. The English king, Edward II, assembled a formidable force to relieve it. This attempt failed, and his army was defeated in a pitched battle by a smaller army commanded by the King of Scots, Robert the Bruce.