al-Nakba: the Palestinian "Catastrophe"

Over 100,000 refugees of the 1948 Nakba fled north into Lebanon, populating 16 UNRWA refugee camps, including Sabra and Shatila where terrible massacres later occurred.  Palestinian resistance groups formed and conducted resistance operations against Israel, drawing Israeli retaliation into Lebanon.  In 1964 The Palestinian Liberation Organization was established in Jordan as an umbrella organization coordinating numerous resistance groups that conducted cross-border operations against Israel.  This led to a crackdown by the Jordanian government in the "Black September" violence of 1970 and expulsion of the PLO from Jordan in 1971, whereupon they moved to Beirut.  The increased Muslim population exacerbated tension and political rivalry with Lebanese Christians, and PLO-launched operations against Israel led to numerous attacks and incursions by the IDF. These events attracted Syrian involvement to defend Lebanon that compromised Lebanese leadership and complicated matters further. The most tragic outcomes of these festering wounds originating in the Nakba were two brief but brutal wars launched by Israel.  The first, in 1982, led to the formation of Hezbollah as a defensive force against Israeli invasion and occupation of southern Lebanon, which Israel justified as defensive against guerilla activities.