After the bombing of Pearl Harbor, Japanese forces invaded the Philippines and promptly issued their own currency, while declaring the Filipinos' money invalid. In response, emergency currency was printed by guerilla fighters and free provinces. These plucky freedom fighters exemplified the proverb, "necessity is the mother of invention" as the various peso denominations were printed using whatever paper and inks were available. If Japanese soldiers caught citizens with any amount of those emergency notes in their possession, they would pay the ultimate price and be put to death. Set of 10 different genuine emergency notes.