I've got a new essay, "War and Liberalism," just out in The New Republic.
The main argument of the piece is that historically liberal government "has turned out to be stronger and more effective in war than its adversaries have expected, and ... more resilient under the pressures of war than liberals themselves have feared."
One of the main reasons that democracies have a better record in war than dictatorships do is that democracies rarely begin wars that they cannot win, and win quickly According to the historical pattern, the Iraq War should never have happened. Why it did and why it has gone so badly and done so much damage to America's interests are all immensely revealing about what is wrong with the conservatism of the Bush era.
Here is the concluding paragraph:
There is a different way of thinking about power from the one that conservatives in the Bush era have championed, and that way of thinking grows out of the liberal tradition and historical experience. The crucial historical lesson is not that liberal principles and public debate must give way in war for the sake of national defense: constitutionally limited power has proved to be more powerful than unlimited power. Democratic partnerships at home and abroad are critical to the nation's strength. America has risen to its current position partly on the basis of these ideas, and staying true to them would be a victory in itself.