The bombing of Gernika (or Guernica in Spanish) during the Spanish Civil War happened on this day in 1937, less than a month after Durango nearby was also bombed.
Again, like Durango the people were targeted although the Germans claimed they were aiming for Factory and war related sites which explains why they decided to carpet bomb the centre and destroyed houses and churches instead, and killed anything up to over 1500 people (the figure is still disputed to this day).
Gernika is famous also for the painting titled Guernica by Pablo Picasso which is currently in the Reina Sofia art museum in Madrid. For those unlucky enough to follow me on twitter or as a friend on facebook, you may have noticed there is a copy in the back room of Tasca el Corral which is a sideria bar in Carrer Merce in Barcelona.
Not going to give the ins and outs but this wiki page can give you enough info on what happened that day (quite a thorough review).
RIP all those who died that day