The Convention of Estates, 1643-4
At times when the King had not authorised a full assembly of the Scottish Parliament (the "Estates of Parliament"), a Convention could be called for a specific purpose, usually to raise taxes or to pass temporary legislation to be ratified by a later Parliament. Membership of the Convention was similar to that of the full Estates of Parliament, but a Convention could not pass permanent laws.
In 1643, with the English Civil War at its height, King Charles I was reluctant to allow the Scottish Parliament to meet because he feared that the Covenanters who dominated the government of Scotland were likely to form a military alliance with the English Parliament against him. However, in May 1643, the privy council of Scotland voted to summon a Convention of Estates despite the attempts of the King's representative the Duke of Hamilton to prevent it. In order to save face, King Charles belatedly gave his permission for the Convention to meet but imposed certain limitations. He expressly forbade it to raise a new army in Scotland or to recall Scottish troops stationed in Ulster.
The Convention assembled in Edinburgh on 22 June 1643. A committee was selected to define its powers, drawn from each of the estates: the nobles, lairds and burgesses. In general, the nobles supported Hamilton's insistence that the Convention should adhere to the limitations imposed by the King, but the lairds and burgesses supported the Marquis of Argyll who argued that the Convention should ignore the limitations. The majority favoured Argyll. Hamilton and his brother the Earl of Lanark withdrew from the Convention in protest.
The Covenanters' case for an alliance with Parliament was strengthened when the captured correspondence of the Earl of Antrim revealed details of a plan to instigate a Royalist uprising in Scotland to be supported by a Catholic army from Ireland. Copies of the incriminating documents were forwarded to the Westminster Parliament, where there was already fears of a Royalist-Catholic conspiracy and strong support for an alliance with Scotland. In August 1643, a delegation of English Parliamentarians arrived in Edinburgh to negotiate the treaty known as the Solemn League and Covenant.
Having agreed to the terms of the military and religious alliance with England, the Convention of Estates set up the mechanism for raising an army to be sent to England and appointed its commanders. The Convention then adjourned until January 1644, leaving the Committee of Estates to govern Scotland in the interim. When it re-assembled, the Convention completed arrangements for recruiting and supplying the Army of the Covenant. A reserve army for the defence of Scotland was levied in February 1644. All the acts of the Convention of Estates were ratified by the full Scottish Parliament that met in June 1644.
S.R. Gardiner, History of the Great Civil War vol i (London 1888)
David Stevenson, The Scottish Revolution 1637-44 (Newton Abbott 1973)
C.V. Wedgwood, The King's War (London 1958)