Okinawa Memorial Day is observed in the Japanese prefecture of Okinawa every June 23 to commemorate those who died during the Battle of Okinawa, which was the only ground engagement of the Pacific theater of World War II fought on Japanese soil. The battle lasted from April 1 to June 22, 1945, resulting in the deaths of over 240,000 people, including both Japanese soldiers and Okinawan civilians. The day was first established in 1961 during the American occupation of Okinawa and was later restored as a public holiday in 1991 after Okinawa returned to Japanese sovereignty. On this day, a memorial ceremony is held at the Cornerstone of Peace, a monument dedicated to the victims of the battle, and it is typically attended by the prime minister of Japan. While it is recognized as a public holiday in Okinawa, it is not officially celebrated in other prefectures of Japan.