The Solemn League and Covenant was an agreement between the Scottish Covenanters and the leaders of the English Parliamentarians in 1643 during the First English Civil War. On 17 August 1643 the Church of Scotland (the Kirk) accepted it and on 25 September 1643 so did the English Parliament and the Westminster Assembly. General assent was obtained for the Solemn League and Covenant throughout Scotland and England by allowing the populace to sign it.
The Protestant leaders of the embattled English parliament, faced with the threat of Irish Catholic troops joining with the Royalist army, requested the aid of the Scots. The Presbyterian Covenanters promised their aid against the 'papists', on condition that the Scottish system of church government was adopted in England. This was acceptable to the majority of the English Long Parliament, as many MPs were presbyterians, while others preferred allying with the Scots to losing the Civil War.
After some haggling a document called "" was drawn up. This was in effect a treaty between the English Parliament and its Scottish counterpart for the preservation of the reformed religion in Scotland, the reformation of religion in England and Ireland "according to the word of God and the example of the best reformed churches", and the extirpation of popery and prelacy. It did not explicitly mention presbyterianism, and included some ambiguous formulations which left the door open to the English Independents, another strong faction on the English Parliamentary side, particularly in the parliamentary armies. It was subscribed to by many in England, Scotland, and Ireland, approved by the English Long Parliament, and, with some slight modifications, by the Westminster Assembly of Divines.