When German Zeppelins began bombing England during World War I in history’s first mass aerial assaults, the British were faced with the new problem of how to warn the civilian populace of impending air raids. They experimented with various alternatives including bobbies carrying warning signs through the streets, but such measures were not prominent enough to get everyone’s attention over the din of daily life and hurry them to shelter. After much experimentation someone came up with the idea of using mortars firing blanks to alert the populace. Nothing beats the sound of gunfire for urging people to shelter, so the mortars proved very effective and were quickly implemented.
That left the problem of sounding “all clear” after each attack, however. Obviously no one is likely to leave shelter at the sound of mortar fire, so another approach was needed. Bobbies on bicycles were tried, yelling “all clear” while riding through the streets, but too few of the citizenry could hear them from places of shelter. Ultimately British authorities found a workable solution — to sound the all-clear following WWI air raids, police drove open cars through the streets, carrying boy scouts blowing bugles. ©2009 Gregory N. Brown