Klaas de Vries, born in Franeker on December 15, 1875, son of Jelle de Vries and Sijke de Vries, pilot's apprentice.
Klaas was married in Harlingen on May 26, 1904, at the age of 28 to
Ymkje Reinhart (aged 23 years), born in Harlingen on December 11, 1880, daughter of Hendrikus Reinhart (warehouseman, workman and dock hand) and Johanna Brouwer.