After Israel declared its independence in 1948, it was attacked by the neighboring Arab countries, resulting in the Arab-Israeli War. At the end of this war, the city of Jerusalem was divided. Israeli forces controlled most of the city and East Jerusalem, including the Old City, was controlled by Jordanian forces. The Old City was important for strategic and religious reasons, as many sites of religious importance are in this part of the city. These include the Dome of the Rock and al-Aqsa Mosque (Muslims); the Temple Mount and the Western Wall or Kotel (Jewish); and the Church of the Holy Sepulchre (Christian).
On June 7, 1967 Israeli forces captured the old city of Jerusalem. This resulted in the reunification of Jerusalem as part of Israel. According to the Hebrew calendar, it was the 28th day of the month of Iyar in the year 5727 and the anniversary of this date is known as Yom Yerushalayim or Jerusalem Day. (www.timeanddate.com/holidays/israel/yom-yerushalayim)