During the Second World War he fought in the 101st Jäger Division, which suffered massive losses on the Eastern Front, and his combat experiences inspired his first successful novel, Das geduldige Fleisch (1955), published in English translation as The Willing Flesh in the United Kingdom and as The Cross of Iron in the United States (1956).

Over the course of the war, the 101st Jäger Division suffered seven hundred percent casualties – Heinrich himself was wounded five times.

[2] After the war, Heinrich became a writer; his first novel In einem Schloss zu wohnen, written 1950–1952, went unpublished until 1976, when he was an established novelist.

In 1977, Sam Peckinpah adapted it as the film Cross of Iron, featuring James Coburn as the protagonist anti-hero Rolf Steiner.

Most of his books are novels, but Erzählungen (1985) is an anthology comprising three novellas: Die Freundinnen, Fata Morgana, and Harte Bandagen.