On this day in 1859, three stamps were issued for the Ionian Islands. Located off the west coast of Greece, the group was a British protectorate from 1814 to 1864. The stamps are in denominations of 1/2 d, 1 d, and 2 d. The denominations are identified only by the stamp's colors, which are orange (1/2 d), blue (1 d), and carmine (2 d). Intaglio printing was by Perkins, Bacon & Co. The stamps were designed by Charles Henry Jeens (E). The first stamp (orange) has no watermark, while the other two stamps have numerals 1 and 2 as watermarks. All three stamps are imperforate. 50,000 of each denomination was printed, and many forgeries of the stamps exist. 

Examples of the stamps

In 1915, semi-postal stamps were issued for the French island of Martinique. Martinique is an island located in the West Indies, southeast of Puerto Rico. Formerly a French colony, it became an integral part of the Republic, acquiring the same status as the departments in metropolitan France, under a law effective January 1, 1947. The stamps had a denomination of 10+5 French centimes and were used to raise funds for the Red Cross. Click here to see more stamps of Martinique from our reference collection.

An example of the stamp

Three years later, The U.S. Post Office  Department established the first air mail service between Washington, Philadelphia, and New York. The world's first purpose-designed air mail stamp had been issued May 13 for this service. This is the stamp of which the inverted center variety is one of philately's best-known errors. The 24c per ounce mail rate included a special delivery service. On July 15, the rate was reduced from 24c per ounce to 16c per ounce for the first ounce and 6c for each additional ounce. This included a 10c special delivery fee. On December 15, the rate was once again reduced to 6c per ounce but did not include a special delivery service.

In 1922, Finland issued its first semi-postal stamps. Much like the stamps of Martinique, this stamp was also used to help raise money for the Red Cross. Two varieties of the stamp exist, one with perforation of 14 (655,650 printed) and one with 13*13.5 (10,000 printed and sold after the expiry date of the original stamp). The stamps were used for domestic mail exclusively. The design featured Finland's national coat-of-arms in the oval, with a red cross over the lion.

An example of the stamp

In 1929, Nicaragua issued its first airmail stamps. Printed by American Bank Note Co., New York, these are definitive stamps with the overprint "Air Mail" and P. A. A, which is an acronym for Pan American Airways, which is an airline company that is no longer in operation. 

The first Nicaragua airmail stamp set

Also of note, May 15, 1972, is the earliest known use date of the USPS Officially Sealed label bearing the USPS logo instead of the familiar head of liberty.