Hostilities began in February, 1639 when a band of Covenanters attacked and claimed the city of Aberdeen. About the same time, the Campbells of Argyll, supporting the National Covenant, attacked clan Macdonald, who were Catholics.

  Charles led an army of nearly twenty thousand men northward during the spring of 1639. He met a Scottish force that was better trained and disciplined than his own at Berwick. The Scottish army was commanded by General Alexander Leslie. The so-called First Bishop’s War was settled without a fight by the King agreeing to allow another General Assembly of the Scottish Parliament to be held. He also agreed to an Assembly of the Church.

  The Scottish Parliament, in session before the Assembly of the Church, began with ratifying the acts of the previous General Assembly, but they were not satisfied with simply reenacting that which had already been enacted. It went so far as to completely abolish the episcopacy and to demand that all Scots pledge their allegiance to the Covenant. A Triennial Act ensured that the Parliament would meet every three years, with or without the King’s blessing. Another act stated that all public officials would be appointed by the Parliament rather than by the King. The Committee of Articles, which had been created by King James IV as a means by which the King could controll the Scottish Parliament, was declared void. In effect, the acts passed by the Parliament in this second General Assembly declared Scotland free from the royal government of England.

  Leslie and his army of Covenanters pushed southward across the River Tweed during the summer of 1640. They easily defeated Charles’ army near Newburn and then marched into Newcastle-upon-Tyne in what was called the Second Bishop's War. The terms Leslie gave to Charles, to which he readily agreed, was that the Scottish army be paid for its upkeep; in effect the payment was a tribute. Charles returned south to summon the English Parliament to request the raising of funds for that purpose.

  The new regime in power, the Scottish Parliament under the guidance of Archibald Campbell, the Earl of Argyll, was not necessarily well liked throughout Scotland. As is the case with any revolution, there were many Scots who did not wish to drop their allegiance to King Charles. There were the Anglicans who opposed the Covenant from the beginning. And then there were factions which simply opposed the leadership of the Earl of Argyll. One of those factions would be headed by the Earl of Montrose.

  In August of 1640, eighteen noblemen met a Cumbernauld to form the Cumbernauld Bond, with the Earl of Montrose at their head. This group felt that the Earl of Argyll was using the Parliament for his own benefit. The Covenanters army under Leslie was staunchly in support of the Scottish Parliament and did not see Argyll as an opponent, so for the time being, Montrose and the other members of the Cumbernauld Bond had no hope of taking control. (Montrose would, in 1644, part completely with Argyll and cross over in support of Charles.)