Thistle is the national flower of Scotland, which may be related to this story. In the 13th century, there was a war between Denmark and Scotland. Denmark surrounded the Scottish city and wanted to invade it along the city wall. So the soldiers were naked and planned to cross the moat to attack the city. Unexpectedly, the trench was dry. At first glance, there were thistle fields. The soldiers who stepped into the thistle fields wailed because they could not bear the pain. When the Scottish army detected this situation, it launched an attack, broke through the siege and won a complete victory. Since then, "thistle" has been regarded as the flower to save the country and as the symbol of the country.