The other theories were good, but I ahve one more to add for your consideration. I’m sure many of you who are either “new age” or followers of “the old religion” (you know who you are) have heard of runes- the ancient Norse alphabet that was used for divination purposes, much like tarot. These Runes were also used in talismans to help prevent something from happeneing, or to encourage something to happen. One of the simplest talismans was a rune inscribed inside of a circle. The Rune “eolh” looks remarkably like the peace sign (two arms raised and a line through the middle), means friendship and is used for protection. In the midst of wars and whathaveyou, a little friendship and protection were probably just what everybody was looking for. Before somebody pops off with “Yeah, but the rune would be UPSIDE DOWN in the peace symbol- therefore making it a NEGATIVE symbol! So there!” there is no upside down, or reversed meaning in a talisman. If the intention is to bring about harmony, etc. then the only consideration is the asthetic value of the talisman.