In the evening he went with his older brother, the Master of Winton, to the lodging of the Earl of Eglinton with nine or ten companions.

The Master of Winton and the Earl passed each other, but the servants at the rear of the two companies started to fight, only because of a long-standing feud between the Eglinton and Glancairn families.

Montgomerie's uncle Alexander Seton called the three-year struggle for his nephew's earldom "this over langsome and fashious besines of Eglintoun".

[4] Montgomerie petitioned against the imposition of Common Prayer Book in Scotland and assisted in the preparations of the National Covenant.

Montgomerie, who was commonly known as Greysteel,[5] commanded a Scottish regiment of horse (cavalry) for the English Parliament and distinguished himself at the Battle of Marston Moor (1644).