For hundreds of years, inverted flags have been harnessed as a signal of distress. Hoisting the ensign upside-down was also a potentially covert way in which sailors might share that their ship had been taken by hostile forces and was being manoeuvred nefariously. The United States Flag Code expresses the idea concisely, stating that a flag should never be flown upside-down, “except as a signal of dire distress in instances of extreme danger to life or property.”