He is known for his historical paintings, but his most-recognized work is his illustration on behalf of the German Emperor Wilhelm II, Peoples of Europe, Guard your Dearest Goods, which has become an iconic symbol of the use of the yellow peril to justify European imperialism in Asia at the end of the nineteenth century.
Early in his career, his paintings were characterized by a sometimes pedantic-looking realism that focused on small details such as the historical accuracy of the costumes.
One commission was People of Europe, Guard Your Dearest Goods, based on a rough sketch by Wilhelm[2] that highlighted his fear of the yellow peril after the end of the First Sino-Japanese War.
[5] Knackfuss also traveled extensively to Greece, Spain, Italy, Asia Minor and Egypt, and accompanied Emperor Wilhelm II to Palestine in 1898.
Knackfuss died of typhus in 1915 during World War I while serving as a guard at the Niederzwehren POW camp in Kassel.