Basically, I would divide Snyder's 8 Myths of Empire in to two camps. One is a class of myths which say that an imperial power must go to war now, the other is the myth that say this war will be easy and quick. The myths are the following:
1) Offensive Advantage: War with country X is inevitable, so it's best to attack soon. Armies on the offensive have the advantage. This was used by the Germans and Japanese during World War II, and for the Germans it was a repeat from WWI. It is, however, historically dubious. Armies on the offensive, at least in the 20th century, have a pretty poor record.
2) Power shifts: War with country X will permanently remove a challenger to an imperial power's strength. Again, historically dubious. Germany's 20th-century belligerence created more enemies, and therefore made Germany's imperial power less secure, not more.
3) Paper Tiger enemies: Country X is vulnerable and will be conquered with a minimum of risk to our side. This one is classic, and proven wrong over and over.
4) Bandwagoning: Other countries will see our display of strength, and rush to our side either out of fear or allegiance. Again, historically illiterate. Like the "power shifts" argument above, offensive wars tend to create counter-balancing, not bandwagoning.
5) Big Stick diplomacy: Potential allies will be persuaded by threats. For example, Germany's attempts to forestall a Russo-French alliance by threats against France - the intention being to show France they couldn't rely on Russian or British support. In fact, Germany's threats solidified the Triple Entente.
6) Falling Dominoes: Small reversals at the frontier show weakness to the enemy, and need to fought with all means. You can pick a bunch of historical examples, such as Fashoda or Vietnam, but my recent example would be Chavez and Venezuela. Frankly, there's no reason to care what Chavez does - he's a minor player, even by the standards of Latin American politics. Yet he is vocally anti-American, and he sits on a bunch of oil. And Washington, for almost a decade now, has been obsessed with him. Why? My thought is simply that he presents a challenge at the frontier, and Washington is worried about what happens if his influence grows in South America.
7) El Dorado: The conquest of territory X will be low-cost, or even profitable, because of massive resources there. See the Greater East Asian Coprosperity Sphere for the most blatant example of this. Also, Wolfowitz' famous claim that Iraq could finance it's own development.
8) No Compromises: Any one of myths 1-7 is insufficient, but all of them combined leave only one choice: war. It's not enough to say a war with X is going to be profitable - you need to show that war is inevitable, allies will support you, etc etc. As Snyder says:
The Bush Administration's strategic rhetoric about Iraq in late 2002 did not disappoint in this regard. Saddam was portrayed as undeterrable, as getting nuclear weapons unless deposed and giving them to terrorists, the war against him would be cheap and easy, grumbling allies would jump on our bandwagon, Iraq would become a democracy, and the Arab street would thank the United States for liberating it. In real life, as opposed to the world of imperial rhetoric, it is surprising when every conceivable consideration supports the preferred strategy. As is so often the case with the myths of empire, this piling on of reinforcing claims smacks of ex post facto justification rather than serious strategic assessment.You're probably not surprised to hear me say, yes, that the salesmanship underlying the Iraq War was classic Snyder. Snyder says as much in the article I linked to. The reason I bring this up is as a warning to Dems and other lefties in the US - the Democrats have, historically, been just as vulnerable to these seductive myths as anyone. (Vietnam being a Democratic war.) But when the support for an aggressive foreign policy is based on these kinds of statements, it's a sign that the policy being proposed is almost certainly a disaster in the making.