On January 19, 1915, a German Zeppelin raid against two cities in Great Britain brought a taste of what was to come, both in the First World War and the Second.  While casualties and damage were limited, but the impact on morale was pronounced.  Rumors of spies and secret bases swirled, and with no effective air raid shelters, everyone must have gone to bed wondering if tonight was the night.

Germany followed up the January attacks with multiple raids on London and other military and industrial cities in Great Britain and France throughout the war, using both Zeppelins and airplanes.  While they did damage, the effectiveness of these attacks was arguable, at best.

Strategic bombing in the age before guided bombs or even effective bomb sights was wildly inaccurate, so stating a militarily necessary target was more of a formality.  It must have been a given that in order to attack a given target, some amount of civilian deaths would have to be planned.  Even in this age of laser and GPS-guided bombs and missiles, non-combatants get hurt or killed.  The difference is, to me, that modern planners do what they can to reduce the risks to those who should not be harmed.