Lebanon

Ongoing civil war, currently sub-acute, together with repeating conflicts with Israel, since 1970s.
 
Independence from France came in 1941, leading to a complex post-colonial ethnic-religious national covenant. Four main ethnic-religious groups exist in Lebanon (involving 16 minorities): Shi’a Muslim, Sunni Muslim, Druze and Maronite Christian.
 
Many Palestinian refugees entered Lebanon from 1948 onwards, destabilising the ethnic balance. Near civil war broke out in 1958 - a Muslim-Christian conflict over power and privilege. Israeli attacks on Palestinians (PLO). Multi-sided civil war 1975-90, with American, Israeli and Arab foreign involvements. Syrian intervention in 1976, partly strategic, partly as a mediator.
 
Israeli invasion of South Lebanon in 1978, again in 1982 (against Palestinians and Shi’as) - notorious Israeli-supported Christian massacres of Palestinians at Sabra and Shatila refugee camps. Israel withdrew in 1985, leaving a proxy occupation by the Christian SLA and guerrilla war with Shi’a Hezbollah in south Lebanon.
 
In 1988-90 came the final phase of the civil war: breakdown of government, Muslim-Christian division of Beirut and a Christian war against the Syrians. Defeat of the Maronite Christians brought peace, leading to a renewed national covenant and rebuilding of Beirut (president Hariri).
 
Low-level conflict between Hezbollah, Israel and SLA in the 1990s, leading to an Israeli invasion of south Lebanon in 1996-2000. Shi’a Hezbollah become the dominant power in the south. Syrian withdrawal came after the controversial assassination of PM Rafiq Hariri in 2005.
 
Devastating war between Israel and Hezbollah 2006 (nominal Hezbollah victory). Since then, there has been an uneasy peace, with political paralysis and rivalries between Shi’a and Sunni elements, most recently in 2008, as Sunni groups try to constrain the growing power of Hezbollah.
 

Links:

Global Security: Lebanon Civil War 1974-91
INCORE: Lebanon Country Guide
Human Rights Watch: Israel-Lebanon War 2006
International Crisis Group: Lebanon Conflicts
Reuters Alertnet: Lebanon Crisis