Classifying the 1-cent stamp, as well as the 2-cent and 3-cent stamps of the National Defense Issues, has always presented a problem for stamp collectors. Issued as propaganda stamps for World War II, the Post Office Department issued billions of them and asked postmasters to sell these denominations instead of the Presidential regular series stamps in circulation at the time.
Originally to be issued on October 12, 1940, in Washington, DC, the first day of issue was delayed until October 16, "National Registration Day." On that day over 16 million men and women registered their names in support of the "National Defense Program."
President Franklin Roosevelt sketched the first, rough concept for the 1-cent Liberty, and Bureau of Engraving and Printings designer William A. Roach developed FDR's concept further. The Bureau printed billions of these stamps, and in the process some of the perforating wheels became worn. It is thought that, since those who maintained the printing equipment properly were off fighting the war, post offices received stamps with partial perforations. Part-perfs and imperfs appeared in huge numbers in post offices around the country, and they became the twentieth century's most extensive errors or freaks ever delivered for retail sale at US post offices.