He became field-marshal in the imperial army and his division, along with Stefan Czarniecki's division, Frederick William's army and Danish forces, participated in the struggle in Denmark against the invading Swedes.
From 1661 to 1664 Montecuccoli, with inferior numbers, defended Austria against the Turks but at St. Gotthard Abbey, on the Rába, he and Carl I. Ferdinand Count of Montenari defeated the Turks so comprehensively that they entered into a twenty-year truce.