Yglesias refers to a section on Habsburg history in the second part of Paul Schroeder’s article on Iraq in TAC as an “annoying detour,” which I suppose it might be for some people, were it not for the fact that the “annoying detour” was a central part of explaining Prof. Schroeder’s key insights into the essential flaws of the Iraq war.  Here is Prof. Schroeder:

Austria’s leaders were convinced that it was defending not just itself but the rights of all of Europe against international outlaws and that every decent government in Europe, understanding this and appreciating their stand, would support them even if it led to war. This moral hubris, the absolute value they assigned to Austria’s just cause, closed their minds not merely to political and strategic realities but also to competing moral values and judgments. Many Europeans understood Austria’s grievances but placed a higher value on peace, recognized other rights besides historic and legal ones, and understood the necessity and inevitability of change.

The same three strategic errors—a refusal to recognize when a position has become untenable, a reliance on military victory and power to achieve unattainable ends, and moral hubris leading to political and strategic miscalculation—have also brought the U.S. into its current mess in Iraq. 

It might also be worth noting at this point that Prof. Schroder is a modern European history professor who probably has relevant insights into lessons from the history of defunct empires.  Those would be some of those “annoying detours” Yglesias mentioned.