At the battle of Falkirk in 1298, William Wallace (aka "Brave Heart") abandoned the guerrilla tactics that served him so well at Stirling Bridge, and adopted a strong, but "conventional" defensive position featuring formations of spearmen. The Scots were outnumbered two to one, and were badly beaten by the English "combined arms" of cavalry, archers, and pikemen.
One can dismiss this as a "mistake" except that Robert Bruce adopted (superficially, at least) somewhat similar tactics against similar two to one odds at Bannockburn in 1314 and won.
Was there something in the terrain at Bannockburn that made a decisive difference compared to Falkirk? For instance, the marshy ground around Bannockburn (and Stirling Bridge) may have proved more of an obstacle to English cavalry than at Falkirk?
Also, long bowmen apparently made the difference in favor of the English at Falkirk (and later against France in the 100 Years' War), but not at Bannockburn. Why would that be?
Finally, is it true that the Scottish "camp followers" that the English despoiled on their way to Bannockburn formed an "army" of sorts (Pat Buchanan's "peasants with pitchforks"), and hit the English from behind, or at least threatened their supply train while they were facing main the Scots army under Bruce?