The story behind the coin
Germany in 1877 was six years old as a nation and still arguing about its own money. The Coinage Act of 9 July 1873 had swept away a continent's worth of thalers, guilders and kreuzers and put one currency in their place: the Mark, divided into a hundred pfennigs, with the middling values struck in .900 silver.
The small silver did not settle. The 20 Pfennig piece was pulled and replaced with cupro-nickel in 1877. The 50 Pfennig, launched in 1875, had its imperial eagle redrawn that same year — the "large shield" type gave way to a "small shield" type, catalogued today as Jaeger 8. In a mint doing that much redesigning, somebody asked an obvious question: if the coin is worth half a mark, why does it say fifty pfennigs?
So they struck a trial. Probe is the German word — a pattern piece, made to test a design, a metal or an idea before anyone commits to millions of them. The 1877 half-mark trials take the exact reverse layout of the circulating 50 Pfennig, a value inside a wreath of oak leaves with the year beneath, and swap the wording to ½ MARK.
The idea lost. Fifty pfennigs stayed on the coin through the 1896–1903 revival of the type, and then the denomination simply stopped. When the value returned to the coinage in 1905, the inscription read ½ MARK — the name a mint worker had already punched into a die twenty-eight years earlier.

