On the day after the British Mandate expired, on 15 May, five neighbouring Arab states invaded and rapidly occupied much of the Arab portion of the Partition Plan, and threatening to take the whole of Palestine. In the introduction to the from the Secretary-General of the League of Arab States to the UN Secretary-General on 15 May 1948, the Arab League gave reasons for its "intervention": "On the occasion of the intervention of Arab States in Palestine to restore law and order and to prevent disturbances prevailing in Palestine from spreading into their territories and to check further bloodshed". The invasion changed the dynamic of the region, transforming a two-state plan into a war between Israel and the Arab world.