Yes, there are a few clear examples. The most famous is the Trojan Horse—Homer and later writers describe how the Greeks used the legend of a “giant wooden horse” to trick the Trojans into bringing it inside their walls, which turned the tide of the war. It’s a myth that was deliberately employed as a stratagem, and the story is recorded in the Iliad and other ancient sources. A more historically documented case is the Battle of Legnano in 1176. The Lombard League’s forces claimed they were carrying the True Cross, a relic that had become a powerful legend. According to contemporary chronicles, the sight of the Cross on the battlefield boosted the troops’ morale and helped secure a decisive victory against the Holy Roman Emperor, which in turn shifted the diplomatic balance in northern Italy. Both cases show how legends, when invoked in the right moment, can alter the outcome of a conflict.