Saint Olaf’s Day is observed in some Northern European countries, particularly Norway and the Faroe Islands, every July 29. This holiday commemorates the anniversary of the death of King Olaf Haraldsson of Norway, who was killed in the Battle of Stiklestad in 1030. He is remembered for his martyrdom, which significantly contributed to the establishment of Christianity in Norway, and he is often referred to as Norway's Eternal King. The day, known as Olsok, meaning “Olaf's vigil” or “Olaf's wake,” was a major church holiday before the Lutheran Reformation and has been an official flag flying day in Norway since 1930. While the holiday is still recognized in the Faroe Islands, it is also remembered in Denmark, Sweden, and Finland, although it is not an official holiday there.