The two commanders, John Comyn and Simon Fraser, led a Scots force on a night march, fell on the English, capturing Segrave and several others.

[3] Scottish historian John of Fordun wrote a description of the fight: ...there never was so desperate a struggle, or one in which the stoutness of knightly prowess shone forth so brightly.

But John Comyn, then guardian of Scotland, and Simon Fraser with their followers, day and night, did their best to harass and to annoy, by their general prowess, the aforesaid kings officers and bailiffs...

But the aforesaid John Comyn and Simon, with their abettors, hearing of their arrival, and wishing to steal a march rather than have one stolen upon them, came briskly through from Biggar to Rosslyn, in one night, with some chosen men, who chose rather death before unworthy subjection to the English nation; and all of a sudden they fearlessly fell upon the enemy.The battle was the subject of a fictional account written by Walter Bower in the mid-15th century.

A monument cairn erected by the Roslin Heritage Society at the end of the 20th century marks the site of the battle.