unoverprinted uses are known. Also, some offices failed to comply with orders and simply sold their stamps unoverprinted. In 1864, the system was refined by shipping the stamps from Mexico City with an invoice number and year already overprinted. Sometimes the district office's overprint included a number designating the suboffice for which the stamps were intended, and occasionally suboffices applied their own handstamps. Larger offices had several different designs of handstamp in use; Mexico City used five different devices to handstamp the stamps of 1856, each with a different appearance, while the districts of Guadalajara, Guanajuato, Puebla, Querétaro, and San Luis Potosí each had three devices. The color of the district name was almost always black, but red, blue, and violet overprints are known. For a period in 1858, the postmaster of Zacatecas, who had fled the city for Aguascalientes to escape the fighting during the Reform War, but had left his handstamp, wrote in "Zacatecas" by hand. For many years, philatelists were mystified by the overprints, until Samuel Chapman, a British businessman living in Mexico, took an interest and researched the postal archives. His 1926 book, since reprinted, includes extensive detail on the shipments to the various districts. Many of the overprints are rare, and command high prices among specialists in Mexican stamps. They have also been forged. Postal cancellations After stamps were introduced in 1856, some post offices created new cancellation marks, while others used their existing handstamps bearing the name of the town for years to cancel the new stamps, so that very old handstamps can be found on stamped covers. Postage stamps Hidalgo issues 1856 and 1861 President Don Ignacio Comonfort, authorized the prepayment of postage using adhesive stamps by decree of February 21, 1856. New regulations were drawn up and were supposed to be published on July 15, but problems with the engraving delayed this until July 31. On August 1, 1856 Mexico issued its first postage stamps. The design, a portrait of Miguel Hidalgo y Costilla, the parish priest who led an unsuccessful bid for Mexican independence in 1810, reflected the reform politics of the Comonfort government. The stamps were somewhat crudely engraved and imperforate. Five values were issued from 1856-1859; ½ real, 1r, 2r, 4r, and 8r. The stamps usually, but not always, had district overprints with the name of the district post office. Quantities produced according to Follansbee: ½ real blue -