The Long Parliament was first called by King Charles I on 3 November 1640 soon after the dissolution of the Short Parliament and the defeat of the English in the Bishops' Wars against Scotland. The King was reluctant to summon another Parliament but the expense of the wars had left him desperately short of money and in need of parliamentary subsidies. Although purged and then expelled during the Commonwealth and Protectorate years, the Long Parliament was not formally dissolved until 16 March 1660.
During the early 1640s, Parliament's opposition to the King was spearheaded by John Pym but criticism focused upon his advisers rather than the King himself. At Pym's instigation, the Earl of Strafford and Archbishop Laud were denounced as "evil councillors" and impeached within weeks of the Long Parliament first assembling.
During 1641, a series of reforms was carried out which abolished the courts of Star Chamber and High Commission and other institutions that had allowed the King to rule without calling a Parliament during his eleven-year Personal Rule. Unpopular measures such as ship-money, forced loans and destraint of knighthood were also abolished. The Triennial Act was passed to ensure that Parliament would be called at least once every three years. The reforms carried out by the Long Parliament eventually formed the basis of the Restoration Settlement and were important steps towards the constitutional monarchy and parliamentary democracy of modern Britain.
The Irish Uprising of October 1641 brought into sharp focus the critical issue of whether the armed forces should be controlled by the King or by Parliament. A new Militia Bill was proposed in Parliament but this was strenuously resisted by the King. His disastrous attempt to arrest the Five Members in January 1642 highlighted the extent of the rift. In March 1642, the Long Parliament decreed that its own ordinances were valid and legally binding, without the need for the King's assent. With the complete breakdown of dialogue between Parliament and the King, civil war became inevitable.
Around one-third of the members House of Commons and most of the House of Lords left Westminster to join the King's alternative Oxford Parliament in 1643. From 1645 onwards, "recruiter" elections were held to "recruit" or make up the numbers of MPs at Westminster.
Parliament organised local government of the shires and counties through a system of committees ("commissions") and individuals. Local justice continued to be administered by the High Sheriff and Justices of the Peace, and local militias continued to be organised by commissioners for the militia. The Long Parliament set up a county committee in each shire which was responsible for directing the county's affairs in general. Additional committees were set up to administer estates witheld ("sequestered") from Royalists, to oversee the clergy and to levy Parliament's property tax (known as the "assessment"). Membership of the various committees often consisted of the same people and in some counties powerful individuals emerged who dominated the county administration.
During the course of the First Civil War, the Long Parliament became divided over whether hostilities should be settled by negotiation with the King, or by inflicting a decisive military defeat on him. The "peace party" was associated with the Presbyterian faction in Parliament; the militant "war party" was associated with the Independents. These factions were also divided by their differing approaches to religion. They were not organised political parties in the modern sense.
After the end of the First Civil War, the victorious New Model Army became a political force in its own right. The army's involvement in the political process began over the reluctance of the Presbyterian majority in Parliament to settle arrears of pay and other grievances of the soldiers. After the Second Civil War in 1648, the army, with the connivance of some Independent MPs, carried out Pride's Purge to exclude Presbyterian sympathisers. The Purged Parliament became popularly known as the Rump Parliament. This body governed the republican Commonwealth after the execution of King Charles and the abolition of the Monarchy and the House of Lords. However, army leaders grew impatient with Parliament's slow implementation of radical policies, and the Purged Parliament was expelled in April 1653, to be replaced by the short-lived Nominated Assembly and the Protectorate of Oliver Cromwell.
The Purged Parliament met again after Cromwell's death and the collapse of the Protectorate in 1659. The surviving members who had been excluded at Pride's Purge were recalled in February 1660, thus restoring the Long Parliament for its final session. This body voted on 16 March 1660 to dissolve the Long Parliament and to hold new elections. The pro-Royalist Convention Parliament that assembled in April 1660 prepared the way for the Restoration of the monarchy.