To look at the causes of the First War of Independence you need to go quite far back from its outbreak in 1296. As a kingdom, Scotland lacked some of the royal and religious privileges of England. It did not have its own archbishopric, whilst England had two. Within the structure of the Catholic Church, every church was part of a diocese led by a bishop, and every diocese was part of an archdiocese led by an archbishop. Without a Scottish archbishopric, the English archbishops of York claimed that the Scottish Church should be under their authority. The Scottish kings also lacked the right of unction. For kingdoms like England and France, a new king was crowned and annointed with holy oil, a right they had been granted by the Pope. The Scottish kings had no such right until 1329, limiting their recognition as kings. These shortcomings of the Scottish Church and kingship allowed the English to repeatedly push a claim that they were the overlords of Scotland, that the Scottish Church should be subordinate to the archbishop of York, and that the Scottish king, lacking a proper papal coronation, was a petty king subordinate to England.

England's claim to overlordship was first pressed in 1174 with the Treaty of Falaise. The Treaty was signed between King William I of Scotland and Henry II of England. William had been captured whilst fighting in northern England and was forced to agree to this treaty. The document made William declare the English kings as his overlord and also ceded several Scottish castles to Henry. William's chief vassals were also to swear loyalty to Henry. This was the first major attempt by the English to claim overlordship of Scotland.

In 1189 William managed to buy his way out of the Treaty of Falaise. Richard I of England was in need of money to fund his crusade, and agreed to the Quitclaim of Canterbury. Under this agreement, William no longer had to owe fealty to England, neither did his vassals, the castles were also given back to Scottish control. In return, William paid Richard 10000 marks (£6666). However, this treaty did not force England to renounce all claims of overlordship, it just reverted things to the pre-1174 status quo, when England still had some arguments in favour of their superiority.

For much of the thirteenth century, relations between England and Scotland were good. The nobility of each country had lands in both kingdoms, including the Scottish royal family. Henry III's (ruled 1216-72) sister, Joan, married the Scottish king Alexander II, and Henry's daughter, Margaret, married Alexander's son, Alexander III (ruled 1249-86). Henry often acted in a paternal manner to Alexander III, helping him during his early reign when he still too young to rule independently and a series of warring nobles ruled on his behalf. When intervening in Scottish politics in 1251 and 1255 he even promised that this did not prejudice Alexander's rights as king. In the civil wars in England of Henry's later reign, Alexander sided with the king and was raising an army to support Henry when he heard of the war's end. Alexander made repeated trips to England, as did Henry's son, Edward. When Edward became Edward I in 1272, this relationship continued. In 1278 Edward's councillors suggested that Alexander should owe Edward fealty for his kingdom, Alexander refused, and Edward accepted this.

This seemingly stable situation spiralled out of control in the last years of Alexander III's life. In 1280 his son David died, followed by his daughter Margaret in 1283, and another son, Alexander, the year after. The king's wife had died in 1275 and he had not remarried. Alexander III still had one heir, the child of his daughter Margaret, called Margaret, Maid of Norway, but she was only born in 1283. Alexander, however, was just 42, and so remarried in the hope of securing another heir. He married a French noblewoman, Yolanda of Dreux, in 1285. On the night of 19th March 1286, during a thunderstorm, Alexander rode out from Edinburgh and crossed the Forth. Travelling through Fife to the royal manor where his wife waited, the king was thrown from his horse and broke his neck.

Margaret was declared the new queen of Scotland, but she was still in Norway, and only two years old. A group of nobles were declared guardians, and ordered to rule on the queen's behalf. Initially this included two bishops, the earl of Fife, two members of the Comyn family and one of the Stewarts. The two main families with claims to the throne, the Bruces and Balliols, were not included. Robert Bruce (grandfather of Robert I of Scotland) led a minor rebellion 1286, but this ended with him swearing fealty to Margaret.

Margaret's father, Eric II of Norway, was reluctant to send her to Scotland as he did not fully trust the guardians (many of whom were close associates of the Bruces or Balliols). Edward I eventually persuaded Eric to send Margaret to Scotland by promising to marry his son Edward to her. After negotiations between the English, Norwegians, and Scots in November 1289, the marriage was agreed to. Margaret arrived in Norwegian-ruled Orkney in September 1290 and died soon after, never setting foot in her kingdom.

Uproar broke out in Scotland. In early October Robert Bruce led another armed march on a gathering of the guardians and other nobles at Perth. They were dissuaded by English envoys and the Balliols, who began gathering their own supporters. Civil war threatened to break out. Both sides turned to Edward I for resolution. A parliament was called with representatives of both kingdoms. At that gathering in May 1291, Edward declared that he would hear both sides and decide the succession, but as Scotland's overlord. Despite resistance to this idea, all the claimants eventually agreed to Edward's terms. Claims to the throne now came from Robert Bruce, John Balliol, Edward himself, the count of Holland, and John Hastings, an English magnate. Whilst the case was being heard, Edward acted as the overlord of Scotland, running the royal administration and granting lands.

The case ended on 17th November 1292, when Edward granted the kingdom to John Balliol. Balliol soon swore fealty to Edward as his overlord. Balliol's role as Edward's servant was not to last. Edward antagonised the Scottish nobles by demanding that they support him in a war with France. Also, as overlord of Scotland, Scottish nobles could now resolve their disputes in Edward's court instead of Balliols. One particular court case became the pretext for war. Duncan, earl of Fife, had been murdered in 1289, and since then the earldom had been managed by the bishop of St Andrews. In 1292 the next heir to the earldom, Macduff, complained that the bishop was preventing him taking custody of the land. Edward ordered that Macduff resume control but when Macduff attempted to do so, Balliol had him summoned to parliament and imprisoned. Edward demanded that Balliol explain himself but the Scottish king declared that he did not recognise Edward's authority in what should have been an internal Scottish matter. Relations soured with England and Balliol's son, Edward, was married to the French king's neice.

In early 1296 Edward issued a final summons for Balliol to answer for Macduff's arrest. The Scots ignored this and the First War of Independence between England and Scotland finally broke out in March that year when Edward's army captured the Scottish town of Berwick.

The basis for the wars can be found in the ambiguities of Scotland's status as a kingdom, the contested independence of its church, and the interconnections of the Scottish and English aristocracies. But this only provided a potential basis for matters to develop further. The deaths of Alexander III and his heirs provided the opportunity for England to play the role of peacemaker and assert its overlordship of Scotland. Finally, the Macduff case became the trigger for the War, giving Edward I a pretext to invade Scotland and enforce his authority over Balliol.

Sources:

Michael Brown, The Wars of Scotland 1214-1371 (Edinburgh, 2004).

E. L. G. Stones and Grant G. Simpson (eds), Edward I and the Throne of Scotland 1290-1296 (Oxford, 1978), two volumes.

Lucinda H. S. Dean, 'Crowning the Child: Representing Authority in the Inaugurations and Coronations of Minors in Scotland, c. 1214 to 1567', in Sean McGlynn and Elena Woodacre (eds), The Image and Perception of Monarchy in Medieval and Early Modern Europe (Newcastle, 2014), pp. 254-280.