The story behind the coin
The change looks like bookkeeping, and in a way it was. Germany's imperial currency had been built in 1871 on the Mark of 100 Pfennig, and for thirty years the biggest small-silver piece in everyday pockets was the 50 Pfennig. After 1903 no more were struck. From 1905 the same value came back with a new name on its face: ½ MARK.
Why bother? Because the Mark, not the Pfennig, was the unit the whole system was reckoned in — the answer to a Germany that until 1871 had counted in thalers, guilders and kreuzers depending on which border you stood behind. Calling the coin half a Mark made the point that the Mark was the measure of things. It is a small piece of metal doing a piece of political tidying-up.
Then history caught up with it. The ½ Mark was struck straight through the First World War, when silver became something the public wanted to keep rather than spend, and small change drained out of circulation into drawers and jars. Striking continued into 1919 — by which point Wilhelm II had abdicated and the Empire was gone, though the coins still read DEUTSCHES REICH, a name the new republic kept. On 20 April 1920 the ½ Mark was withdrawn, and it was demonetised the following January. Inflation was already eating the paper Mark alive; a silver coin with a fixed face value could not survive that.

