When Poland regained its freedom after the First World War, Father Heyke was based from 1920 to 1935 in Kościerzyna, where he served as chaplain and teacher of religion and French at the National Gimnazjum.

He resumed his prolific publication of poetry and historical works, preferring to emphasize northern variants of the Kashubian language.

After the German invasion of Poland on 1 September 1939, Father Heyke attempted to join the Polish Army as a chaplain.

However, he was arrested by the Germans in the Kociewian town of Wda and executed with other clergy and intellectuals on 15 October in the Szpęgawski Forest near Starogard Gdański.

Although Father Heyke's works were rarely published during the period of Communist rule, his life and writings now enjoy a renewed recognition in Kashubian culture.