In 1286, by the time he was about sixteen, Wallace may have been preparing to pursue a life in the church. In that year, Alexander III died after riding off a cliff during a wild storm. None of Alexander III's children survived him. After his death, his young granddaughter, Margaret, the 'Maid of Norway', was declared Queen of Scotland by the Scottish lords, but was still only a little girl of 4 who was living in Norway. An interim Scottish government run by 'guardians' was set up to govern until Margaret was old enough to take up the throne. However, Edward I of England took advantage of the uncertainty and potential instability over the Scottish succession. He agreed with the guardians that Margaret should marry his son and heir Edward of Caernarvon (afterwards Edward II of England), on the understanding that Scotland would be preserved as a separate nation.

Margaret fell ill and died unexpectedly in 1290 at the age of 8 in the Orkney Islands on her way from Norway to England. 13 claimants to the Scottish throne came forward, most of whom were from the Scottish nobility.

Scotland was essentially occupied by the English at this time, and was beset by its own internal conflicts. The various aristocratic Scottish guardians of the throne plotted against one another, variously aligning themselves with King Edward or defying their loyalty to him when it suited them. At the same time English troops, including mercenaries and frequently disgruntled Welsh and Irish conscripts, operated freely throughout Scotland from stockaded camps and fortified garrisons. Civilian life was precarious, and abuses by the occupiers against the common people were rife. The Scottish nobles did little to maintain the rule of law and protect Scots from atrocities.

In this climate of lawlessness, William Wallace's father was killed in a skirmish with English troops in 1291. It is likely that the death of his father at the hands of the English contributed to Wallace's lifelong desire to fight for his nation's independence. However, little is known about Wallace's life during this period, except that he lived the life of an outlaw, moving constantly to avoid the English, and occasionally confronting them with characteristic ferocity.

Carrick's describes Wallace's skills as a warrior:

"All powerful as a swordsman and unrivalled as an archer, his blows were fatal and his shafts unerring: as an equestrian, he was a model of dexterity and grace; while the hardships he experienced in his youth made him view with indifference the severest privations incident to a military life."

In the absence of a clear successor to the Scottish throne, the claimants to the Scottish throne requested Edward I's arbitration. The three main candidates were all descendants of David, Earl of Huntingdon, who was the brother of William the Lion, king of Scotland from 1165 to 1214. John de Balliol was the grandson of David's eldest daughter; Robert de Bruce was the son of David's second daughter, and John de Hastings was the grandson of David's youngest daughter. In 1292, Balliol was chosen as king by a special commission one half of whose whose members were chosen by Bruce and the other half by Balliol.

Balliol took an oath of fealty, paid homage to Edward, and was accepted in Scotland. However, Edward I's motives had not really been to help the Scots as an arbitrator. He saw himself as the feudal superior of the Scottish crown, and wished to install a Scottish monarch whom he could manipulate.

Edward underestimated the Scots' belief in their own sovereignty. When he sought to exert his suzerainty by taking law cases on appeal from Scottish courts to his own court in England, and by summoning Balliol to do military service for him against France, he turned the Scottish throne against him. In the meantime, England had been at war with France. In 1295, a treaty was negotiated between Edward I and the French that provided for the marriage of John de Balliol's son Edward to the French King's niece. Edward demanded the surrender of three castles on the Scottish border and, on John's refusal, summoned him to his court. John did not obey, and war was inevitable.

Edward marched north with his armies. After a five-month campaign, he conquered Scotland in 1297. Following his victory, he appointed his own agents to enforce peace in Scotland. He deposed and imprisoned John de Balliol and declared himself ruler of Scotland. He also had the Stone of Destiny, the coronation stone of Scone, taken south to Westminster. The government of Scotland was placed in the hands of Englishmen led by Hugh Cressingham, the Earl of Surrey.

Outside the south-east corner of Scotland, there was widespread disorder, and defiance against the English was increasing. Wallace was involved in a fight with local soldiers in the village of Ayr. After killing several of them, he was overpowered and thrown into a dungeon where he was slowly starved. Wallace was left for dead, but sympathetic villagers nursed him back to health. When he had regained his strength, Wallace recruited several local rebels and began his systematic and merciless assault on the hated English and their Scottish sympathisers.

As his support grew, Wallace's attacks broadened. In May 1297, with as many as 30 men, he avenged his father's death by ambushing and killing the knight responsible and some of his soldiers. Now, he was no longer merely an outlaw but a local military leader who had struck down one of Edward's knights and some of his soldiers. William Wallace had become the king's enemy.

Although most of Scotland was in Scottish hands by August 1297, Wallace successfully recruited a band of commoners and small landowners to attack the remaining English garrisons between the Rivers Forth and Tay. Wallace and his co-leader, Sir Andrew de Moray, marched their forces towards Stirling Castle, a stronghold of vital strategic importance to the English. The English commanders must have been falsely confident that the upstart Scots would retreat or surrender. On Sept 11, 1297, the English army under John de Warenne, Earl of Surrey, confronted him near Stirling. Wallace's forces were greatly outnumbered, but Surrey had to cross a narrow bridge over the River Forth before he could reach the Scottish positions. Wallace's men lured the English into making an impulsive advance, and slaughtered them as they crossed the river. English fatalities are reported to have approached 5,000, gaining Wallace an overwhelming victory. He had shown not only that he was a charismatic leader and warrior, but also that his tactical military ability was strong. Never before had a Scottish army so triumphed over an English aggressor. Wallace captured Stirling Castle and for the moment Scotland was almost free of occupying forces.

At the time of the battle of Stirling Bridge, Wallace and de Moray were both in their late twenties. Neither could yet claim to be Scottish national heroes, and they were not recognised by their aristocratic enemies in Scotland as anything more than local commanders. Under Wallace, the Scots, - commoners and knights, rather than nobles, - were united in a focused fight for freedom from foreign rule. Whereas the Scottish nobility had usually given in to English demands for allegiance, Wallace's patriotic force remained unequivocally dedicated to the struggle for Scottish independence.

In October of 1296, Wallace invaded northern England and ravaged the counties of Northumberland and Cumberland. Upon returning to Scotland early in December 1297, he was knighted and proclaimed guardian of the kingdom, ruling in Balliol's name. In less than six years, he had risen from obscurity to become Sir William Wallace, holder of one of the most powerful posts in the kingdom. Nevertheless, many Scottish nobles lent him only grudging support, and he had yet to meet Edward I in a head-on confrontation.

Wallace's acclaim following the battle of Stirling Bridge was short-lived. Edward returned to England from campaigning in France in March 1298. On July 3 he invaded Scotland, intending to crush Wallace and all those daring to assert Scotland's independence. On July 22, Edward's 90,000-strong army attacked a much smaller Scottish force led by Wallace near Falkirk. The English army was at a technological advantage. Its longbow-men decimated Wallace's spearmen and cavalry by firing scores of arrows over great distances. As many as 10,000 Scots may have been killed. Although Edward failed to subdue Scotland completely before returning to England, Wallace's military reputation was ruined. He retreated to the thick woods nearby and resigned his guardianship in December. He was succeeded as guardian of the kingdom by Robert de Bruce (later King Robert I) and Sir John Comyn "the Red".

From the autumn of 1299 until 1303, nothing certain is known about Wallace's activities. There is some evidence to suggest that he went to France with several loyal supporters on a diplomatic mission to seek support from King Philip IV. Philip may have furnished him with letters of recommendation to Pope Boniface VIII and King Hakon of Norway. Then, in 1303, the Treaty of Paris effectively ended hostilities between England and France.

Having made peace with the French, Edward renewed his conquest of Scotland in earnest. He captured Stirling in 1304, and although most of the Scottish nobles pledged allegiance to the English crown, he continued to pursue the outlaw Wallace relentlessly. Edward's refusal to acknowledge Wallace as a worthy enemy from a separate country meant that the English could officially regard Wallace as a traitor to the English nation.

On Aug 5 1305, Wallace was betrayed by a Scottish knight in service to the English king, and arrested near Glasgow. He was taken to London and denied the status of a captured soldier. He was tried for the wartime murder of civilians (he allegedly spared "neither age nor sex, monk nor nun"). He was condemned as a traitor to the king even though, as he correctly maintained, he had never sworn allegiance to Edward.

On 23rd August 1305, he was executed. At that time (and for the next 550 years), the punishment for the crime of treason was that the convicted traitor was dragged to the place of execution, hanged by the neck (but not until he was dead), and disembowelled (or drawn) while still alive. His entrails were burned before his eyes, he was decapitated and his body was divided into four parts (or quartered). Accordingly, this was Wallace's fate. His head was impaled on a spike and displayed at London Bridge, his right arm on the bridge at Newcastle-upon-Tyne, his left arm at Berwick, his right leg at Perth, and the left leg at Aberdeen. Edward may have believed that with Wallace's capture and execution, he had at last broken the spirit of the Scots. He was wrong. By executing Wallace so barbarically, Edward had martyred a popular Scots military leader and fired the Scottish people's determination to be free.

Almost immediately, Robert I the Bruce revived the national rebellion that was to win independence for Scotland. He succeeded and was crowned king of Scotland in 1306.

On his way to reconquer Scotland, Edward died near Carlisle.

Several hundred years later in the 19th century, statues commemorating Sir William Wallace were erected overlooking the River Tweed and in Lanark. In 1869, the 220-foot high National Wallace Monument was completed on a hill near Stirling. This huge tower now dominates the area where the Scots fought their most decisive battles against the English in the thirteenth and fourteenth centuries at Stirling Bridge and Bannockburn.

Following the re-discovery of William Wallace's seal in 1999, the Ayrshire case has began to gather momentum. The seal identifies Wallace as the son of Alan Wallace and not Malcolm and Alan Wallace appears in the Ragman Roll of 1296 as a 'crown tenant in Ayrshire'. Dr. Fiona Watson in 'A Report into Sir William Wallace's connections with Ayrshire' (March 1999), carries out a detailed reassessment of William Wallace's early years and concludes 'Sir William Wallace was a younger son of Alan Wallace, a crown tenant in Ayrshire'. On reading this report the renowned Wallace historian, Andrew Fisher, concedes 'If the Alan of the Ragman Roll was indeed the patriot's father, then the current argument in favour of an Ayrshire rather than a Renfrewshire origin for Wallace can be settled' 

Much has been written about the nature of Menteith's relationship with Wallace, and his precise role in Wallace's capture. It is unlikely that it will ever be settled beyond doubt.

Some argue that no reliable evidence for the betrayal exists. Lord Hailes and Sheriff Mark Napier, a descendant of Sir John Menteith, argue that tradition and Blind Harry's allegation are the only pieces of evidence supporting the charge of betrayal. John Hill Burton, Historiographer-Royal for Scotland, contends that the betrayal story is merely "part of the romance of Wallace's career that he was betrayed by a fellow countryman and an old companion in arms." Even if the betrayal story is true, Burton says that Menteith would be excused as he was Governor of Dumbarton Castle.

On the other hand, others argue that the documented evidence has merit. Sir William Fraser, author of Red Book of Menteith, claims to have examined many of the documents concerning the subject and is of the opinion that the accusation that Menteith betrayed Wallace rests upon insufficient evidence. The documents which Fraser examined suggests the following: