On January 19th 1915 two Zeppelins crossed the North Sea to perform a strategic bombing raid on the UK.
The Zeppelins were intended to target Humberside - Kingston-Upon-Hull being at that time a major seaport - but due to strong winds they were unable to and instead as a result bombed King's Lynn, Great Yarmouth and Sheringham, as well as the surroundings.
Although only four people were killed and sixteen injured, this caused a panic, being a completely new experience in war - attack from the air by an enemy across a sea. In real terms, the raids throughout the war had little effect.
Image: See page for author [Public domain], via Wikimedia Commons (commons.wikimedia.org/wiki/File:LZ_18.jpg)