They lit fires in the surrounding mountains to guide the Luftwaffe into Belfast.
http://markhumphrys.com/sfira.tyranny.html#ww2
http://blog.z-word.com/2009/01/gaza-jewish-legislator-in-ireland-compared-to-goebbels/
I had to laugh at the part that said the IRA lit the fires but the Luftwaffe did not notice! Typical of the disorganized nature of this crack “army.”