In Germany, Plockhorst is mainly known to experts today, whereas his pictures are still very popular in the United States and their reproductions can be found in many American homes and churches.

From 1866 to 1869 he was a professor at the Grandducal Saxonian Art School (Großherzoglich-Sächsische Kunstschule) in Weimar, where painter Otto Piltz was one of his pupils.

In 1872, Plockhorst exhibited a painting which was soon regarded as his chief work, “The Battle of archangel Michael with Satan for the body of Moses” (today in the Städtisches Museum, Cologne).

Later, it was to be exhibited in England, but on September 3, 1880 the ship Sorata, with the painting on board, was stranded on rocks between Adelaide and Melbourne, drawing water into its hold to a depth of 5.5 metres.

When the Melbourne International Exhibition was prepared in 1880, the art dealer Alexander Fletcher (1837–1914) bought the painting for a trifling sum and took it to the restorer George Peacock.

Besides, he portrayed members of the German nobility like Emperor Wilhelm I and his wife Augusta (1888; today in Berlin, National Gallery).