Campert is best known for his poem "Het lied der achttien dooden [nl]" ("The Song of the Eighteen Dead"), describing the execution of 18 resistance workers (15 resistance fighters and three communists) by the German occupier. Written in 1941 and based on an account published in Het Parool, the poem was clandestinely published in 1943 as a poetry card (rijmprent) by what became the De Bezige Bij publishing house[2] to raise money to hide Jewish children.
He was the father of the novelist and poet Remco Campert.