Beginning in 1905, Germany began phasing in the use of watermarked paper on its new issues.
This practice eventually led to the introduction of new Yacht issues which were similar to the 1900 issues, but featured a lozenge-shaped watermark.
The 3 Pf and 1 M values were never postally used due to the fall of German Cameroon. The stamps were only sold at philatelic sales windows in Berlin.
“Peace printings” exist for all except MiNr. 20. “War printings” exist for all except MiNr. 22. The “peace printings” are lighter in color overall, with better quality paper and printing.
In 1923, the Reichspostministerium Markenverwertungsstelle (German Postal Ministry) conducted a sale of old German postage to help fund reparations payments to the Allies. Sale prices varied based on the stamps — the examples shown sold for 3,000 M or 19,000 M (about US$1 at the time due to hyperinflation). The seal on the reverse is the seal of the Reichspostministerium Markenverwertungsstelle.