Gibraltar was affected to a minor degree by the Spanish Civil War. The border between Gibraltar and Spain was secured fairly early in on the war for the Nationalists, who used the nearby port of Cádiz as a staging point for the incoming Army of Africa. As such, the area around Gibraltar was not too near a major front of fighting, and was kept clear of most fighting of the war. However, there were a large number of refugees from Republican Spain arriving to escape the fighting and persecution under both sides, as many as 10,000. The influx of refugees did cause some problems with overcrowding and supplies, due to the small size of the peninsula, however I cannot go into to much detail regarding that as it's not in my area.

Gibraltar was also a security concern for Franco and the Republic, as it was the staging point for the Royal Navy's Non-Intervention patrols around the south of the Iberian peninsula, where regular patrols attempted to block foreign military aid arriving in Spain. As both sides did not wish to antagonise the western powers, and both even competed to gain favour, Gibraltar was under no threat of attack from either side in the Spanish Civil War, despite it being an area which Spain has claimed for quite a while.