Fairbanks received word of the attack on Pearl Harbor via civilian shortwave radio operators who passed the news to the U.S. Army base. More than 200 civil defense volunteers immediately signed up for work that included orchestrating a town blackout, blocking town airfields, and making emergency plans to evacuate the town if attacked. In June 1942, the invasion of the Aleutian Islands and the bombing of Dutch Harbor intensified the war's effect on Fairbanks. Ladd Field's cold-weather testing detachment was disbanded as its soldiers were used to bolster Alaska defenses at other locations.