Wallace meets a woman washing at a well. She says 15 Englishmen who seek him are at the inn. He says he'd go there if he had any money; she gives him some. He goes, disguised, vanquishes the 15, calls for food, is set upon by 15 more and defeats them too.
William Wallace is one of the most famous figures in Scottish history, but surprisingly little is known of him. Prior to the reign of John Balliol, he was invisible; we don't even know his birth date, though many think he was born around 1272 (see Magnus Magnusson, Scotland: The Story of a Nation, Atlantic Monthly Press, 2000, p. 133).
It is only after Balliol was deposed in 1296 that Wallace rose to defend Scotland from Edward I of England's attempts to take over the country. His rebellion apparently started quietly enough: He got into a brawl with some of Edward's soldiers who were at Lanark, and had to flee. A women (possibly his wife) who helped him escape was tortured and killed; Wallace responded by killing a local English officer (see Peter and Fiona Somerset Fry, _The History of Scotland_, 1982; I use the 1995 Barnes & Noble edition; p. 78; Fitzroy MacLean, _A Concise History of Scotland_, Beekman House, 1970, p. 37).
In other times, Wallace might have been called simply an outlaw. But with Scotland an occupied nation, he could call himself a freedom fighter. He declared himself a supporter of John Balliol and raised a rebellion.
The higher nobility was almost universally indifferent. They weren't happy with Edward I, but they had made terms with him, even if at sword point, and weren't willing to risk more fighting. But Wallace was able to gather a band of small landowners and minor knights. In 1297, they met an English army at Stirling Bridge, the last place it was possible to cross the Forth without boats. The English under the Earl of Surrey started to cross the bridge in the presence of Wallace's army (Magnusson, pp. 135-138), and of course he destroyed the portion across the bridge and won a major victory -- E. Thornton Cook, _Their Majesties of Scotland_, John Murray, 1928, p. 91, says the bridge broke under the fleeing English, though Magnusson, p. 139, makes the more reasonable suggestion that Surrey ordered it destroyed.
It was not a complete victory for the Scots; Wallace's chief lieutenant Andrew de Moray was mortally wounded in the battle (Magnusson, p. 139), and many English garrisons held out. But the Scots had shown they could still fight -- an immense pschological boost. As a result, Wallace became a Guardian of Scotland, and obviously respectable (see Rosalind Mitchison, _A History of Scotland_, second edition, Methuen, 1982, p. 43). People even called him "William the Conqueror" (see Colm McNamee, _The Wars of the Bruces: Scotland, England and Ireland, 1306-1328_, Tuckwell Press, 1997).
But Stirling Bridge had been fought while Edward I was away campaigning against France. He came rushing back, assembled an army, and himself led it. And Wallace, the guerilla, tried to fight a set-piece battle at Falkirk in 1298, and was disastrously beaten by Edward (MacLean, p. 38). Edward, no fool, assembled an army of bowmen, cavalry, and infantry, while Wallace had little but spearmen, arranged in schiltrons. Fifteen years later, at Bannockburn, it would be demonstrated that the schiltrons could beat off infantry or cavalry. But Edward I was not the military incompetent his son was. He had, and used, his longbowmen -- the first real use of the weapon that would later bring the English to the brink of victory in the Hundred Years' War. The bowmen broke up the schiltrons, then the cavalry swept up the scattered remnants (Magnusson, pp. 143-144). The Scottish army had ceased to exist. Wallace survived, but from Guardian of Scotland he fell to being a fugitive outlaw; he soon resigned his guardianship and went into hiding (Magnusson, p. 147).
Wallace supposedly went on to try to negotiate with France and the Papacy on behalf of Balliol (Magnusson, pp. 148-149). If so, he was largely ineffective -- indeed, it's hard to imagine them dealing with a man who hadn't even been a knight until so created, perhaps unofficially, after he became a guerilla.
Edward had pretty well pacified Scotland by 1303. Wallace spent the rest of his life on the run, with a price on his head (a hundred pounds, according to Magnusson, p. 152). He betrayed and captured in 1305, subjected to a kangaroo trial in England (the charge was treason, even though he had never taken an oath to Edward I, and the trial, according to Magnusson, p. 155, consisted simply of a recitation of the charges followed by conviction and sentence; Edward I, that alleged paragon of justice, did not so much as allow a statement by the defence), and executed with torture (Fry/Fry, p. 79).
That much is fact -- and it's about all the fact we have. Edward I tried to blot out his memory and leave no relics (hence the treason indictment and the destruction of Wallace's body, according to Magnusson, pp. 157-158), and even the histories sponsored by the Bruces and the Stuarts tried to ignore him (Magnusson, pp. 162-163). Wallace, after all, made Robert Bruce look inconsistent; Bruce's ancestors had competed against John Balliol, and Bruce himself had at times worked with the English.
It was only later that Wallace became a true national hero -- meaning that his legend was created after the facts were almost completely lost. Our Scottish sources, such as Blind Harry's "Wallace," are largely hagiographic, and make Wallace larger than life -- literally; Blind Harry says that he was two and a quarter ells tall, or 83 inches=6'11" or 2.1 meters (Magnusson, p. 133). Scotland's National Wallace Museum has an artifact called (almost certainly falsely) Wallace's Sword; it is 1.7 meters long, or 5'7" (Magunsson, p. 126). Magnusson, pp. 146-147 also notes how many alleged Wallace relics there are around Scotland -- most notably a Wallace Oak, but just as Robin Hood in England gathered wells and churches and trees named after him, so did Wallace in Scotland. This ballad seems to be another example of that; Child notes that the incident is found in Blind Harry's Wallace, though I suspect the ultimate inspiration was the tale of Wallace's wife and how her treatment caused him to become an outlaw.
Wallace's influence is still being felt today; Magnusson, p. 159, notes that when a referendum was held to re-create a Scottish parliament in the late twentieth century, the date chosen for hte referendum was September 11, 1997 -- the seven hundredth anniversary of the Battle of Stirling Bridge. - RBW