King Charles I and the Scots reached a secret agreement in December 26, 1647, known as the Engagement, where by the Scots promised to support his restoration in exchange for him accepting Presbyterianism in Scotland and imposing it in England for three years.
This pact led to the Second English Civil War in 1648. However, the Scottish army under the Earl of Hamilton was defeated by Oliver Cromwell at the Battle of Preston. The loss ultimately contributed to Charles I's execution on January 30, 1649 by beheading, after being found guilty of treason.
