Why did the arab armies invade israel in 1948?

After the defeat of the Ottoman Empire in the First World War, the UN guaranteed the British and French temporary administration of the Ottoman provinces. These regions, which under the Ottoman rule were called vilayatos, were divided into mandates: France came to control the Syrian, while the United Kingdom administered the mandates of Mesopotamia (later Iraq) and Palestine. This region, whose borders were repeatedly revised under the direction of Winston Churchill, was divided into two areas: the eastern part of the Jordan River became known as Transjordan (which in 1950 would be named Jordan), while the area Western continued to keep the name of Palestine. In 1922 the population of the mandate (including Transjordania) consisted of 589,200 Muslims, 83,000 Jews, 71,500 Christians and 7600 of other confessions. During all these years Jewish immigration was increasing, largely due to the persecution that Jews suffered in Europe. This immigration, along with the continuing calls for the establishment of a Jewish state in Palestine, was not well received by the Arabs. Under the leadership of Amin al-Husayni, the great mufti of Jerusalem, the local Arabs rebelled against the British and repeatedly attacked the growing Jewish population. These attacks gave rise to various disturbances such as the Palestine mutiny of 1920, the Jaffa mutiny of 1921 or the Palestinian mutiny of 1929, in which 135 Jews were killed in and around Hebron.