Battle of Newburn

‘On 28th August, 1640, the battle of Newburn was fought. The Scots entered the ford, girdle deep, and after silencing the artillery by their superior fire, made their way across the river, and the English fled with a speed and disorder unworthy of their national reputation.’

The text above is from Walter Scott’s “Tales of a Grandfather”.  The Battle of Newburn was part of the Second Bishop’s War.  Scottish Covenanters under General Alexander Leslie were victorious in this fight against English Royalists under Lord Edward Conway.

Pacification of Berwick

...The Presbyterian form of religion, though deprived of the weight formerly attached to its sentences of excommunication, and compelled to tolerate the coexistence of Episcopacy, and of sects of various descriptions, was still the National Church; and though the glory of the second temple was far inferior to that which had flourished from 1639 till the battle of Dunbar, still it was a structure that, wanting the strength and the terrors, retained at least the form and symmetry, of the original model...

From Walter Scott's "The Heart of Midlothian".  The passage above describes a period beginning with the Pacification of Berwick, which occurred on June 18, 1639.

The Pacification of Berwick ended the First Bishop's War, which pitted England's Charles I, who favored a bishop-led episcopalian form of church government for Scotland, against Scots interested in a bishop-free presbyterian church.

Charles' efforts to impose a new liturgy on Scotland began with the introduction of the Anglican Book of Common Prayer in 1637.  This led to a riot in Edinburgh, instigated by a woman named Jenny Geddes, who threw a stool at a minister in St. Giles Cathedral.

By 1639, Covenanters on the Scots side were skirmishing with Charles' forces.  There was little bloodshed, however.  At Berwick, Charles drew troops of 18,000 against Covenanter forces led by Alexander Leslie.  Rather than fight, both sides determined they had not enough advantage, and a truce was drawn.

Montrose

...' There is but One,' said Allan M'Aulay ; ' and here,' he said, laying his hand upon the shoulder of Anderson, who stood behind Lord Menteith, ' here he stands !'

The general surprise of the meeting was expressed by an impatient murmur; when Anderson, throwing back the cloak in which his face was muffled, and stepping forward, spoke thus :—' I did not long intend to be a silent spectator of this interesting scene, although my hasty friend has obliged me to disclose myself somewhat sooner than was my intention. Whether I deserve the honour reposed in me by this parchment will best appear from what I shall be able to do for the King's service. It is a commission, under the great seal, to James Graham, Earl of Montrose, to command those forces which are to be assembled for the service of his Majesty in this kingdom.'...
 
Walter Scott published "A Legend of Montrose" in 1819.  His named subject, James Graham, 1st Marquis of Montrose, was executed at Mercat Cross in Edinburgh on May 21, 1650.  The Wars of Montrose which transpired between 1639 and 1645 form a backdrop for the novel.
 
As a young man, Montrose became a Covenanter, signing the National Covenant in February 1638.  At least in part what instigated Montrose to join this cause was against the imposition of Laud's prayer book on the Scottish Kirk. 
 
Montrose is best known as a military man, and he gained his first experience leading Covenanter's troops in the First Bishop's War (1639).  After signing the Pacification of Berwick, Montrose ran afoul of Archibald Campbell, who was outwardly supportive of the Covenanters, but Montrose's suspected he had a contrary agenda.  Montrose's opposition to Campbell contributed to an invasion of England under the Second Bishop's War (1640).
 
Montrose corresponded with Charles I after the Bishop's War ended, later opposing the Solemn League and Covenant, which allied Scotland with English Parliamentarians against Charles.  He became a staunch Royalist, which is how Scott portrays him in the novel.