In March 1625 James VI and I died and was succeeded by his son Charles I. Unlike his father, Charles was not interested in uniting his kingdoms - but he was determined to assert his authority in each of them. Early struggles with his Parliament at Westminster came to a head in 1629, and for the next eleven years he ruled by decree without summoning Parliament at all.
The three kingdoms that made up the British Isles were torn by civil wars between 1638 and 1653 when Charles attempted to impose changes on the English and Scottish churches.
In addition there were frequent interventions by each kingdom in the other's internal conflicts:
- in 1641 both English and Scottish troops were involved in suppressing the Irish Catholic rebellion
- in 1642 the Scots invaded Ireland
- in 1643 the Irish intervened in England, and in 1644 in Scotland
- Scottish armies marched into England in 1639, 1640, 1643, 1648 and 1651.
- during 1649-51 the English, under Cromwell, invaded Scotland and Ireland, crushing opposition in both kingdoms
King and Presbyterians
By 1648 the balance of the warring parties had changed. Charles, now in captivity in England, came to terms with the Scottish Presbyterians and their allies in the English Parliament, agreeing to impose Presbyterianism throughout Britain in exchange for their support.
This triggered the second civil war of 1648-9, in which royalists and Presbyterians combined against the New Model Army.
However, the Scots, invading England on the king's behalf, were routed by the New Model Army, under its leader, Oliver Cromwell, at Preston. The Army went on to purge Parliament itself in December 1648.The trial and execution of Charles I followed in January 1649.
On 19 May 1649 Cromwell declared England a Commonwealth and Free State. Scotland and Ireland were later annexed to the English Commonwealth (in a full ‘incorporative’ union) with a single parliament at Westminster.
It was the first time that the Westminster parliament had represented the whole of the British Isles, and 30 Scottish and the same number of Irish representatives sat with English MPs in the 1654 Parliament.
It was primarily a practical arrangement, designed to impose Cromwell's authority, backed up by the threat of force.