On 5 May 1646, Charles I surrendered to the Scottish army at Southwell, effectively bringing the military phase of the First Civil War to a close. Having fled the besieged city of Oxford, the King sought refuge with the Scots in the hope of securing more favourable terms than those he might have received from the English Parliament. This pivotal decision marked the end of his immediate capacity to wage war and shifted the conflict from the battlefield into a protracted and precarious period of political manoeuvring.

The surrender initiated a complex series of negotiations involving four primary factions, each with competing interests and objectives for the future of the kingdom:

• The King, who sought to regain his authority while maintaining his royal prerogative.
• The English Parliament, which aimed to establish a constitutional settlement.
• The New Model Army, which grew increasingly radicalised and distrustful of the King.
• The Scottish Covenanters, who hoped to secure the establishment of Presbyterianism across Britain.

This period of uncertainty highlighted the deep divisions within the coalition that had opposed the Crown. As the Scots held the King in their custody, they found themselves in a difficult position, balancing their religious and political goals against their alliance with the English Parliament. The King’s presence served as a focal point for these tensions, as he attempted to play the various parties against one another to preserve his position. Ultimately, the inability of these groups to reach a consensus regarding the King's future would lead to further instability and the eventual escalation of the conflict into the Second Civil War.