I just came across a concisely stated summary of what can happen in the wake of decolonization and civil war. It's from John Esposito's 2002 Unholy War: Terror in the Name of Islam:
The creation of India and Pakistan resulted in communal warfare that left millions dead. Tens of thousands of Hindus and Muslims were forced to emigrate, Hindus to India and Muslims to Pakistan. Pakistan proved equally fragile. East Pakistan (later Bangladesh) and West Pakistan were separated by 1,000 miles of Indian territory. The difficulty of establishing a strong sense of nationalism in countries with such enormous ethnic, tribal, linguistic, and cultural diversity can be deduced from the fact that in both India and Pakistan the vast majority of the citizens in each country could not speak their national language (Hindi and Urdu respectively). The bloody results of colonial map making and nation creation were evident yet again in the brutal 1971 Pakistan civil war which led to the creation of Bangladesh, and in the bloody ethnic clashes that have threatened the stability of Pakistan to the present day. In Kashmir, the creation of a Muslim majority state within India resulted in wars between India and Pakistan in 1947 and 1965. Since 1987, Kashmiri separatists have been locked in a struggle against India's rule that has brought as many as 750,000 Indian troops to Kashmir to carry out a brutal war. To the present day, Kashmir continues to be a major incendiary issue in relations between India and Pakistan. (my emphasis)
Both of which are nuclear powers, I might add.
With the Iraq War in mind, the above is a reminder of (1) the unpredictability of civil wars; and, (2) the danger in outside powers coming in and stirring up a godawful mess in the first place.
In some of the worst troubles of the world today, we have the "civilizing" mission of the British Empire to thank. It was Britain with help from their imperial partner and sometime rival France that carved up the Middle East after the collapse of the Ottoman Empire in the wake of the First World War. That particular conflict, which was largely a mindless slaughter than the European leaders should have had the decency and good sense to avoid, also brought an end to the Russian, Austro-Hungarian and German Empires.
War can also have wildly unpredictable outcomes. Yet another reason to make it the "last, last, last resort" to solving conflicts, in Wesley Clark's words.
In a real sense, the ethnic/religious conflicts now shaking Iraq are in significant part due to the British schemes for divvying up the Ottoman Empire. Britain tried to maintain a permanent presence in Iraq, too. They finally got tired of the colonial war there and left. (Until that pathetic Tony Blair followed Cheney and Bush back in.)
And, of course, it was during that time that British statesmen in their wisdom made conflicting promises to the Arab and Jewish residents of Palestine. That was a major step toward the post-Second World War decision that the British made, when they finally got tired of fighting Zionist guerrillas/terrorists and left Palestine to the United Nations to solve.
We can speculate that the creation of Israel would have severely antagonized Muslims in any case. But it was Britain who largely shaped the particular form in which that conflict began after Israel was established. Now, the Israeli-Palestinian dispute is s deeply-felt grievance for Muslims all over the world. We can say that's irrational. But of course it's irrational. It's religion. And emotion. And it has real effects in the world, rational or not.
Kashmir, the problem that emerged from the post-British shakeout in what are now India and Pakistan is also a major issue for Muslims, though it's virtually unknown in the United States, it seems.
I'm getting more hesitant all the time about drawing "lessons from history". I can't help but observe that Iraq War supporters would use this bit of history about India, Pakistan and Kashmir as a reason to continue the Iraq War indefinitely. Assuming that FOX News explains some version of it to them, that is.
But the real risk and great likelihood that civil conflict in Iraq will intensify for some period of time after the US leaves isn't in itself reason to stay. We also have to look at the effects of staying. And only in the dream-world of Maverick McCain and like-minded war fans is everything coming up roses in Iraq thanks to The Surge,aka, the McCain escalation.
I wish our Republican zealots had stopped to think about the risk of invading and occupying Iraq before we invaded.