In practice the outcome of WW1 was to mutually impoverish the all the European based empires - with Britain/France as the nominal winners - but with the USA as the real winner by default.  Germany didn't  accept its planned impoverishment - and Japan wanted to get into the game - and so we had WW2.  The USA rather cleverly let the direct combatants exhaust each other somewhat before it came in and cleaned up the remainder.  The UN and the EU emerged to try and prevent a repeat.

The Soviet Union, having suffered horrendously at the hands of Nazism and fearful of invasion wasn't prepared to accept US hegemony, and so we had the Cold War -  effectively a bi-polar world order where all other nations had to choose which side they were on as more or less client states.  Governments which resisted incorporation into one empire or the other were subverted or toppled - by economic, clandestine, or overtly military leans - with major regional conflicts in Korea, and Vietnam.

Remarkably this arrangement proved reasonably stable at a global level: Nuclear war was averted and the conflict largely exported to third world theaters.  Europe and the US thrived, but the Soviet Union couldn't stand the strain of being the sole countervailing power.  So the Soviet Union collapsed and we had Pax Americana -  a Unipolar world order where the US was dominant militarily, economically, politically and culturally/ideologically.

Again a reasonably stable arrangement except that some in the US elite became increasingly arrogant.  The Neo-conservative "New American Century" project basically treated everyone else as a vassal state to be subordinated to US political, military and economic interests.  The end of the threat of socialist revolution meant that the ruling elites could abandon the social democratic/New Deal compromise with the middle/working classes which had provided the basis for post war stability within Europe and the USA. Raw capitalism, red in tooth and claw, once again became the order of the day.

The trouble was that it is very hard to maintain internal stability in an increasingly unequal society without some external bogeyman to scare the populace into conformity with ruling elite interests and norms.  Gorbachev famously commented that "We have taken your enemy away from you - what will you do now?"   So the war against communism was replaced by the war on terror, on drugs, on civil liberties, and on any convenient dictator who could be mustered up to play the bad guy.

Some, like Israel, and perhaps the UK and Saudi Arabia managed to secure a favoured place in this new dispensation - and were very happy to play along.  But others in Europe sought to create a countervailing force through the EU and some states like Russia, China, India, and Iran are beginning to challenge US hegemony.  The US is too thinly spread to control the entire global system on its own, but has been inept at creating alliances whereby other client states do much of the controlling work for it at a regional level.

So we are in danger of reverting to a multi-polar system with all the dangers of inter-imperial competition we had prior to WW1.  However much we might dislike many aspects of US hegemony, American dominance since WW2 has coincided with a period of RELATIVE peace and prosperity around the world (ok - the Vietnamese, Palestinians, Iraqis etc. might not agree).  However this phenomenon may not have all that much to do with American exceptionalism or any particular innate characteristic of the American people, and more to do with the characteristics of a Unipolar rather than a multi-polar world order.

We REALLY don't want to go back to a pre-WW1 type system of international relations with competing Empires creating alliances and waging war on each other. It is a pity the US (under Bush) hasn't shown more foresight and sought to build up the UN and other world organisations to create a system of genuine global governance which can more equally and fairly represent and express the differing interests  within that global world order.  

We need better systems to control war crimes, human rights, regional conflicts, local despots,  global warming, trade, currency exchange, financial services etc. - but having acquired a world empire, the US has been too unwilling to let go of some of that power and allow a more genuinely democratic and balanced world order to emerge.  Critical to the Neo-con project was the destruction of the UN and any attempts to develop a coherent and enforcible body of International Law to which all would be subject as equals.  Even the re-introduction of Government sponsored torture may have had more to do with undermining all international law and conventions than with gaining any actionable intelligence on the ground.

It was to be US rule and with everyone else having to play by the US rules.  Consequently the US is engaged in a series of wars to try and maintain this dominance - and is being weakened in the process.   China, India, Japan, the EU etc. - are not carrying much of the costs of these wars, and thus are growing more economically powerful vis a vis the US all the time.  Sooner or later the US elite need to learn that military/hard power on its own is costly and ineffectual, and that if it wants its values to prevail it will have to cede many of its imperial powers to genuinely global governance agencies.  The tragedy for the US is that Bush has wasted the last 8 years doing the exact opposite. In the meantime economic and political power is gradually slipping away from the US.

The 50 year era of US dominance post WW2 has been relatively peaceful and prosperous, and although obviously unjust in many ways, it is hardly comparable to the old Imperial looters and Hitler and Stalin in their rapaciousness and evil.  There is no guarantee the next 50 years are going to be as stable - especially if we have a serious of resource wars over diminishing oil, food, and water resources.

So we may yet come to appreciate the era of Pax Americana as a relatively benign era - not because the American people are innately morally superior, but because a Unipolar world order worked reasonably well for a time until the arrogance and hubris of the few destroyed it.

The real question is whether we can create a better, fairer and more stable world order as the American empire declines.  Smaller countries like Finland, and Ireland can have a role in this - as they are experienced in the diplomatic skills needed to survive in the shadow of imperial powers.  But the much bigger question is whether the emerging bigger powers can have the vision and leadership to cede enough power to Global bodies which makes a system of international law more robust and enforcible.

If it is to succeed all the major players have to be brought on board.  That is the vision and skill set the US has not, in recent times, demonstrated, even as the unipolar world order has become ever more unstable.  We can criticise the US for this failure, but we in Europe have little to be smug about either, and petty nationalistic finger pointing is hardly the way forward for any of us.