In pursuit of his goal of creating a Prussian-led unified Germany that would dominate Europe, he provoked wars against Denmark, Austria and France.
However, he feared - with good reason - that great power manoeuvring in the Balkans would ignite a European war "from Moscow to the Pyrenees, from the North Sea to Palermo". And when it was all over "we would scarcely know why we had fought".
I wonder how many of the foreign military personnel in Afghanistan, let alone the folks back home, have a clear or even hazy understanding of what they are doing there.
Unlike Iraq with its phantom weapons of mass destruction, the US did have a casus belli - a justification for war: Afghanistan provided al-Qaeda a sanctuary from which to plan and instigate the 9/11 attacks on New York and Washington DC. Whether invading a country half a world away was sensible, proportionate, effective and in America's best interests is another matter altogether.
The invasion had clear objectives: kill or capture Osama bin Laden and dismantle al-Qaeda; get rid of the Taleban; stop Afghanistan being used as a terrorist sanctuary and training ground. Arguably none of these aims was achieved.
Bin Laden is dead, but he was killed almost a decade later in neighbouring Pakistan, America's ostensible ally, apparently under the protection of the Pakistani intelligence apparatus. It scarcely matters whether there are terrorist training camps in the Taleban-controlled areas since there's no shortage of them across the border in Pakistan.
Al-Qaeda might have been ejected from Afghanistan, but it's active in a number of other countries. As for the Taleban, they were toppled but lived to fight another decade. Now it seems just a matter of time before they re-inherit the scorched earth.
Despite his political opponents portraying Barack Obama as unassertive, un-American and deferential to the Muslim world (if not a closet Muslim), he has proved to be a more effective - and cost-effective - killer of terrorist big shots than his trigger-happy predecessor. Obama's policy of targeted assassinations using drones and special forces follows the example of Israel, a country with decades of experience of combating terrorism.
There was another, less trumpeted, reason for being in Afghanistan: nation building. The American-led invaders were going to drag this "broken 13th century country", as a former British defence minister called it, into the modern era.
As the invaders finalise their withdrawal timetables, spare a thought for those Afghans, particularly the women, who took that noble sentiment at face value. The harrowing Time magazine cover photo of a girl whose nose and ears were cut off as punishment for running away from abusive in-laws was a stark reminder that the Taleban's medieval misogyny hasn't abated one iota.
That photo, which appeared two years ago this month, was accompanied by the question: What happens if we leave Afghanistan? The question was largely rhetorical since Aisha's disfigured face provided the answer. It was also somewhat disingenuous since it was clear then, and is even clearer now, that it's a case of when, not if.
The allies' inevitable and inglorious departure from Afghanistan (a broken 14th century country?) will be a textbook example of George Santayana's axiom that those who cannot remember the past are condemned to repeat it.
Britain, the 19th century superpower, came a terrible cropper there culminating in the shambolic 1842 retreat from Kabul. The Soviet Union spent the 1980s trying to eradicate opposition to the communist Government before abandoning its puppets to the Taleban's tender mercies.
This week the Herald ran a wire story reporting that for most Americans Afghanistan has become the "forgotten" war.
The gifted Australian cricketer Mark Waugh spent the late 80s in the shadow of his twin brother Steve, thus earning the nickname "Afghanistan" - the forgotten Waugh.
Different war, same outcome.
