The inconclusive ending to the First Civil War in 1646 led to political turmoil during 1647. King Charles I had surrendered to the Scots. After he was handed over to the English Parliament in January 1647, Presbyterian MPs attempted to disband the New Model Army. Parliament's failure to address the soldiers' grievances resulted in the politicisation of the Army during 1647. The King was seized by Army radicals and London was occupied against the increasing militancy of the Presbyterians. In negotiations to reach a settlement, King Charles exploited divisions between the various factions while secretly plotting to gain military help from abroad. In December 1647, he signed the Engagement with the Scots, promising to impose Presbyterianism in England in exchange for a Scottish army to regain his throne.
During 1648, a number of revolts broke out in England and Wales calling for the return of the King. Several warships defected to the Royalists and garrison troops in Wales rebelled against the government in London. Lieutenant-General Cromwell marched to suppress the insurgency in Wales while General Fairfax marched against the Royalists in Kent and Essex. Fortunately for Parliament, the invasion from Scotland was badly co-ordinated with the uprisings in England and Wales. After Cromwell had defeated the Welsh insurgency, he marched north to defeat the Engagers at the battle of Preston, effectively bringing the Second Civil War to an end.
The Army denounced King Charles for inflicting a second civil war upon the nation. Parliament was purged of the King's supporters and he was brought to trial as an enemy of the people. The King was pronounced guilty and executed in January 1649.