At first. the marines were there to secure the evacuation of the Palestinian Liberation Organization (PLO). But after the MNF. consisting also of French and Italian troops. left in midSeptember. 1982. chaos erupted. On September 14. the Presidentelect of Lebanon. Bashir Gemayel. was assassinated. on September 15. Israeli troops began to enter tie former PLO stronghold in West Beirut. and between September 16 and 18. several hundred Palestinians. and some Lebanese civilians. were massacred by Christian Phalangist forces in two refugee camps. which were under nominal Israeli control. On September 20. President Reagan announced that a force of 1.200 marines would return to Beirut. along with 3.600 other military personnel from France and Italy.