In 1646 Montgomerie was engaged in the northern campaign under John Middleton and on 27 April entered Aberdeen with about 240 horse (cavalry) in four troops.

[1][2] In addition to his horse he had under his command 700 foot in two regiments, and he was entrusted with the duty of holding the city.

[1][3] Huntly, who having suffered some setbacks had retreated to Strathnaver in 1645 had since then returned to his lands around Strathbogie and raised a force of 1,600 foot and 600 horse.

[3][4] Huntly did not remain in Aberdeen, but with his usual indecision he soon returned to Strathbogie.

[4] A council of war declared on 8 June that Montgomerie had conducted himself in the affair "with as much prudence and gallantry as could have been expected".