The Treaty of Berwick was negotiated on 27 February 1560 at Berwick-upon-Tweed. It was an agreement made by the representative of Queen Elizabeth I of England, the Duke of Norfolk, and the Scottish Lords of the Congregation. The purpose was to agree the terms under which an English fleet and army would come to Scotland to expel the French troops who were defending the Regency of Mary of Guise. The Lords were trying both to expel the French and to effect the Scottish Reformation, and this had led from rioting to armed conflict.
The leader of the Lords of the Congregation was the Duke of Chatelherault. He had formerly been Regent, but in this treaty was described as "second person", meaning that he was heir to the throne after Mary, Queen of Scots. His representatives at Berwick were James Stewart, 1st Earl of Moray, Patrick, Lord Ruthven, Sir John Maxwell of Terregles, William Maitland younger of Lethington, John Wishart of Pitarro, and Master Henry Balnaves of Halhill. England's representative was Thomas, Duke of Norfolk.
The treaty was effective, the English navy already had a fleet in the Firth of Forth commanded by William Winter, and now an English army under Baron Grey de Wilton marched north from Berwick into Scotland. On 24 March 1560 Elizabeth had a proclamation published and circulated in English, French and Italian, which detailed her concerns over Mary's use of English heraldry and the ambitions of the Guise family. The proclamation stressed that England was not at war with France or Scotland, although Elizabeth had been forced to "put in order, to her great charges, certain forces both by sea and land."
The English force assisted with the Siege of Leith until hostilities ended in July 1560, after the death of Mary of Guise and the signing of the Treaty of Edinburgh. Under the terms of the treaty, the French fortifications at Leith, new works at Dunbar Castle and at Eyemouth were demolished and the French and English went home. The religious ambitions of the Scottish lords were realised in the Reformation Parliament of August 1560. This parliament also ratified the treaty; William Maitland commended it and the goodwill and favour of Elizabeth in relieving the extreme necessity and "almost utter ruen of the whole countrie." According to the English observer Randolph, there was common consent and some would have happily signed in their own blood.
John Knox thought the treaty so important in explaining the actions of the Lords of the Congregation to posterity that he inserted the whole text into his History of the Reformation. Knox directly related the treaty to the thinking of his colleague Christopher Goodman in his tract, How Superior Powers Ought to be Obeyed, by writing:
And because we have heard the malicious tongues of wicked men make false report of this our fact, we have faithfully and truly inserted in this our history the said contract, …that memory thereof may bide to our posterity; to the end that they may judge with indifference, whether that we have done anything prejudicial to our commonwealth or yet contrarious unto that debtful obedience which true subjects owe to their superiors…
The modern historian Michael Lynch called the treaty "an astonishing document which mentioned many things but not religion." Pamela Ritchie, historian and author of a political biography of Mary of Guise, sees the treaty as facilitating "the interference of a foreign monarch in what was essentially a domestic crisis."
It was planned at first to hold the meeting for the treaty in Scotland on 25 March 1560, at Aitchison's Haven, the harbour of Newbattle Abbey in East Lothian