The Bishops' Wars — Bellum Episcopale — refers to two armed encounters between Charles I and the Scottish Covenanters in 1639 and 1640, which helped to set the stage for the English Civil War and the subsequent Wars of the Three Kingdoms

Rise of the Bishops
For Charles, war with the Scots was a risky strategy. In England he had ruled without Parliament for eleven years and simply did not have the resources for a sustained campaign. Calling a new Parliament was potentially dangerous because of past opposition and current hostility to official policy. Instead the king tried to conjure up a coalition of forces against the Covenanters, to include such armed units he was able to gather in England from his existing resources, the domestic opposition to the Covenanters in Scotland, concentrated in the Highlands and the territory of the Gordons of Huntly in Aberdeenshire, as well as troops from Ireland. Scotland was to be enveloped in attacks from without and within.
Charles' strategy was bold but amateurish: he would advance to the borders of Berwickshire with the royal army, while James, Marquess of Hamilton. led an amphibious force into the Firth of Forth, and Randal Macdonnell, Earl of Antrim, advanced from Ireland against Archibald Campbell, Earl of Argyll, a leading Covenanter. Hamilton was given the supplementary aim of aiding the Marquess of Huntly.
But like all such grand strategies the whole scheme fell apart when confronted by the detailed logistical problems that real soldiers always have to face: the men were badly trained and equipped; transport, especially shipping, was a serious problem; there were few secure bases and insufficient stores; and there was no detailed plan of campaign. Thomas Wentworth, Charles' Lord Deputy in Ireland, did little to disguise his contempt for the mercurial Antrim, and refused to extend the necessary support for the planned invasion of Scotland. The Covenanters, though little better prepared than the king, at least had the advantage of superior morale, defending a cause they believed to be just. All internal resistance to the Covenanters was swept aside in June 1639 when the Gordons were defeated by Montrose at the Battle of the Bridge of Dee, the only serious clash of the whole war.
Charles arrived at Berwick at the end of May, camping with the rest of his army a few miles to the west at a place called Birks on the English side of the River Tweed. Things were far from good. Most of the troops were badly prepared, food was scarce, and disease had broken out. All were tormented by lice, known in the grim humour of the camp as "Covenanters." When the weather turned bad few had any shelter, and for miles there were no trees from which to build huts. Smallpox was an ever present hazard; desertions were frequent. Thomas Windebank, son of the king's Secretary of State, carried his own frustrations to an explosive extent. The only thing that kept out the cold and the wet, he wrote,
…was the hope of; Rubbing, fubbing and scrubbing those scurvy, filthy, dirty, nasty, lousy, itchy, scabby, shitten, stinking, slovenly, snotty-nosed, logger-headed, foolish, insolent, proud, beggarly, impertinent, absurd, grout-headed, villainous, barbarous, bestial, false, lying, rougish, devlish, long-eared, short-haired, damnable, atheistic, puritanical crew of the Scottish Covenant.
On the other side of the border the army of the Scots, commanded by Alexander Leslie were little better off than their English opponents. As Archibald Johnston of Warriston relates, Leslie was short of money, horses and provisions. The stand-off could not last indefinitely, but the Scots were unwilling to cross the border. Even if they defeated the king in battle, their position would not be secure, as English national passions would be aroused. With neither side willing to advance or retreat, the only alternative was to open negotiations.

First Bishops' War (1639)
At Birks, Charles had reached a dead end. His last hope disappeared when he received a letter from Wentworth, saying he could expect no help from Ireland and urging him to delay his campaign for a year. The Earl of Bristol and several other noblemen told him frankly that he would have to summon Parliament if he wished to proceed with his war against the Scots. Realising that his whole strategy was falling to pieces he decided to accept the Scots proposal for negotiations.
Talks began in the Earl of Arundel's tent on 11 June, with six Scottish commissioners—headed by John Leslie, earl of Rothes, Johnston of Warriston and Alexander Henderson—facing a similar number of Englishmen. Soon after they began the King appeared in person, frosty at first, then becoming more relaxed. After Charles promised a new Assembly and Parliament to settle the church question, Warriston responded, by accusing him of playing for time. Although Charles expostulated that "The Devil himself could not make a more uncharitable construction," it is unlikely that anyone believed the peace would be permanent. Both sides agreed to disband their armies, however, and Charles, while refusing to accept the decisions of the "pretended" Glasgow Assembly, agreed to summon a new gathering to meet in Edinburgh on 20 August, followed shortly after by a Parliament. On this basis, the Pacification of Berwick was signed on 18 June. It was only to be a short breathing space.

Peace of Berwick
As expected, the Edinburgh Assembly confirmed all the acts passed at Glasgow, without mentioning its predecessor by name. But it went even further, uncovering the real causes of the contest with the King. It was no longer only a struggle over confessional differences and church government; it was over secular political power as well. Not only was Episcopacy abolished, but churchmen were also declared incapable of holding civil office. Worse, from the King's point of view, the appointment of bishops was declared not only wrong in practice but also contrary to the law of God. (Charles had accepted the argument that Episcopacy might be set aside in the Scottish church as a temporary expedient. However, to declare it contrary to scripture meant that its rejection could not be limited by time or space. If Episcopacy was universally unlawful, how could it be maintained in England and Ireland?) Parliament, which met soon after the Assembly, in effect confirmed a revolution: in Scotland royal power, absolute royal power, was dead.
It was an impossible situation for Charles to accept: he could not rule as a constitutional monarch in one kingdom and hope to retain the powers of an absolute monarch in the other two. For England, the situation was particularly invidious because of its more advanced tradition of constitutional law. For Charles to summon a new Westminster assembly any time before the outbreak of the First Bishops' war would have been a risky enterprise; after the Edinburgh Assembly and Parliament it was a step fraught with suicidal implications.

Primary

Donald, P., An Uncounselled King. Charles I and the Scottish Troubles, 1637–1641, 1990.
Fissel, M. C., The Bishops' Wars. Charles I's Campaigns against Scotland, 1638–1640, 1994.
Lee, M., The Road to Revolution. Scotland under Charles I, 1985.
McCoy, F. N., Robert Baillie and the Second Scots Reformation, 1974.
MacInnes, A. I., Charles I and the Making of the Covenanting Movement, 1991.
Russel, C, The Fall of the British Monarchies, 1637–1642, 1991.
Stevenson, D., The Scottish Revolution, 1637–1644, 1973