The Glasgow Assembly, 1638

The imposition of a new Book of Canons and Prayer Book on the Church of Scotland resulted in the signing of the Scottish National Covenant in February 1638 and demands that a General Assembly of the Kirk should be convened to settle the crisis. During the summer of 1638, the King's commissioner in Scotland, the Marquis of Hamilton, negotiated with the Covenanters, playing for time while the King made military preparations to subdue the Scots. However, the Covenanters made preparations of their own and it soon became clear that the King could not gain an immediate military advantage. On 22 September 1638, a proclamation was issued in Edinburgh summoning a General Assembly for the following November.

King Charles attempted to undermine the Covenanters by issuing an alternative Covenant, known as the "King's Covenant", but it met with little support. Meanwhile, the Covenanters set about managing the election of commissioners to the Assembly and intimidating their opponents. When the Assembly convened in Glasgow Cathedral on 21 November 1638, the Covenanters overwhelmingly dominated the proceedings. After a long and bitter argument with the covenanting lords Rothes and Loudoun over the election, membership and powers of the Assembly, the Marquis of Hamilton declared its dissolution on 28 November.

The Assembly continued to sit in defiance of Hamilton, who called a meeting of the privy council and issued a proclamation confirming and justifying his action. The powerful Earl of Argyll remained at the Assembly, indicating his open support for the Covenanters for the first time. While Hamilton left to consult the King, seven other privy councillors followed Argyll and issued declarations of support for the Covenanters.

With no representative of the King present and any opposition to the Covenanters stifled, the Assembly moved swiftly to nullify all acts and pronouncements of General Assemblies held between 1606-18 because they had been dominated by the King and bishops. Laud's Prayer Book and the new Book of Canons were condemned as unlawful, having not been sanctioned by the Kirk. On 8 December, the Assembly voted to abolish Episcopacy from the Scottish Church and to declare it unlawful; two days later, the "popish" Five Articles of Perth, which had been reluctantly accepted by the General Assembly of 1618, were similarly abolished. All Scottish bishops were deposed and excommunicated. Having affirmed the Kirk's power to summon annual assemblies and calling one to meet in July 1639, the Glasgow Assembly dissolved itself on 20 December 1638. The Covenanter movement had effectively seized power in Scotland.