A red flag

Origin

Imagine the chaos of ancient battlefields or the high seas of the 17th century. Amidst the roar of cannons and clashing swords, a vivid scarlet banner would often be unfurled: the red flag. For centuries, this vibrant hue has been an unmistakable signal of danger, challenge, or defiance. Early Roman armies used red standards, and later, pirates hoisted the 'Jolie Rouge' not just to demand surrender but to announce a fight to the death, promising no mercy. This potent visual of an imminent threat, a stark warning against proceeding, gradually bled from literal battlefields and volatile seas into our everyday language. It became a powerful metaphor for any early indicator of trouble, a clear sign that something is amiss, urging us to stop, look, and reconsider before it's too late.