At the time, the
Protestant leaders of the
English Parliament were in conflict with
King Charles I. Fearing
Irish Catholic troops could join the
Royalist army, Parliament requested the aid of the Scots. The
Presbyterian Covenanters promised their aid, 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 rather than losing the Civil War. taking the Covenant After some haggling a document called "
The Solemn League and Covenant" 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. However, not all those on the English Parliamentarian side were happy with this arrangement and some, like
John Lilburne, chose to leave the parliamentary armies rather than take the oath prescribed in the Act enforcing the
Solemn League and Covenant. The agreement meant that the Covenanters sent another army south to England to fight on the Parliamentarian side in the First English Civil War. When the Scots army entered England by invitation of the English Parliament in January 1644 the Parliamentary
Committee of Safety was replaced by an ad hoc committee representative of both kingdoms which, by parliamentary ordinance of 16 February, was formally constituted the
Committee of Both Kingdoms. Its object was the management of peace overtures to, or making war on, King
Charles I. The Scots withdrew from the committee after the end of the First Civil War, although it continued to sit and from then on was known as the Derby House Committee (as it sat in Derby House in London). ==Engagement and Charles I (Second Civil War)==