After being discharged from the Danish Navy, Christmas joined the Greek Navy in 1895. While enlisted, he was involved in the Greco-Turkish War of 1897. He left the Greek Navy and returned to Denmark in 1897. He rejoined the Danish Navy in 1914 at the rank of captain, but was forced to resign in 1916 due to complications with severe rheumatism. That same year he was inducted as a member of the Order of the Dannebrog.