The last few "theory and practice" posts have focused on the slipperiness of war aims, and the disasters that can result when you lose your grip on them. In short, when it comes to how you fight a war, flexibility is a good thing. Flexibility over goals, however, is usually a polite way of describing confusion. As we've discussed, a nation unclear about why it's fighting, or what victory means, is usually on the proverbial road to ruin. Ending a war is often hard enough; confusion over what constitutes victory makes reaching the end that much harder.
The most pungent example, of course, was the seach for "peace with honor" in the Vietnam War. What was an acceptable peace, and exactly what about the nation's honor was at stake? The bitter disagreements over these questions complicated and delayed the achievement of these goals--however hawks, doves, or someone in between (like Lyndon Johnson) might envision them.
Fortunately, governments have ways to enforce clarity about war aims--tools that are as inescapable as the law, in fact. Formal declarations of war may not be as common as they used to be, but they're useful instruments for defining war objectives.
Of course, the United States hasn't declared a war since 1941. Before getting into the reasons why, let's rewind a bit further in history.
Formal declarations as we think of them have a long history. The Hundred Years War began with Edward III's letter to King Philip VI of France. Edward claimed the French throne was legitimately his, and "we give you notice that we intend to conquer our inheritance by force of arms." At this point in the history of Western Europe, war was a struggle between dynasties, in which the warring parties mobilized forces of mercenaries and anyone who owed a feudal obligation. Later, in the Age of Reason, when states as we think of them first came into being, the sovereign declared war to articulate a change in the relationship with some other sovereign, including the usual list of demands and grievances. Up to this point, declarations of war were communications between leaders, from feudal to absolute monarchs, and were considered part of the normal diplomatic intercourse between these authorities. With the rise of the nation-state, a declaration of war took on a new meaning: a statement made not just between sovereign governments, but to one's own population. The declaration aimed to mobilize the population, justify the losses to come, and explain the goals for which the nation would be fighting.
Not every war, of course, involved a declaration--but most did. The French monarchy's struggle with the Hugenots may not have involved a formal declaration of war, but its earlier battle with the Cathars did--the papacy's blessing of a crusade against heretics. Rebels, schismatics, and other internal enemies often did not deserve the trappings of civilized diplomacy; nor did relations with the infidels. However, a declaration of war, however framed, remained the norm.
States in the 19th and 20th centuries increasingly fell into patterns of fighting "little wars" without formal declarations. The American republic's first protracted war after independence, the struggle with the North African emirates (the so-called "Barbary pirates"), seems to have been the first time the United States fought an undeclared war--very early in its history, during the presidency of Thomas Jefferson. Even though Jefferson evaded the responsibility of going to Congress for a declaration before deploying a squadron to the Mediterranean, he was, in fact, adhering to the conventions of war declarations. Jefferson justified the deployment by saying that it was purely defensive, to protect American shipping. If, once the infant US Navy arrived in the Mediterranean, the commander of the expedition found that a de facto state of war between the United States and the Barbary kingdoms already existed, a de jure declaration of war would be unnecessary. (In fact, the pasha of Tripoli obligingly began hostilities.)
Still, the United States, like other powers, was willing to take military action in small conflicts--Nicaragua, China, Haiti, etc.--without formal declarations of war. However, once the United States emerged as a world power, formal declarations with Spain, Germany, and other enemies certainly were the rule for major conflicts.
What changed this pattern was the Cold War. Declarations of war "plant the flag," creating commitments, raising expectations, and investing prestige. Once a government declares war, it either wins or loses it, in the eyes of the nation. In Korea, the US public certainly wanted a WWII-style total victory, with the aggressor state not only vanquished, but dismantle. US leaders, of course, were worried that escalating the Korean War to the point where we could have won such a victory might have spiralled out of control--a WWI-like dynamic of commitment and escalation among great powers, but now with nuclear weapons.
After 1945, therefore, the United States therefore went to war many times without once declaring war. It's hard to think of Korea and Vietnam as minor conflicts, even though they were "limited wars." However, US leaders still kept clear of the legal and psychological commitments that a declaration of war would have created, preferring instead to look for some other legal instrument (a Congressional authorization, a UN mandate, a mutual protection clause in a treaty) to formally trigger and define the conflict.
The first Gulf War was, arguably, the last major Cold War conflict fought in this fashion. Even though the Cold War was officially over (in fact, the USSR had ceased to exist), the United States was still not sure of the likely Russian reaction.
In 2003, no one seriously believed that Russia or China would come to the defense of Iraq. If the Iraqis did have WMDs, a declaration of war wouldn't have made a difference one way or another: either they would use these weapons to defend themselves, or they wouldn't. (The Bush Administration barely asked for a UN mandate.) The second Iraq War was certainly a major conflict. There was no risk of nuclear retaliation against US cities. The Bush Administration argued that, in the normal terms of foreign relations, the Iraq War was fully justified.
So why didn't the United States declare war?
Even more perplexing is why we did not declare war against the Taliban regime. We had a direct connection between the 9/11 attack, cited as the Pearl Harbor of our time, and the Taliban alliance with al-Qaeda. However, we didn't declare war as we did in 1941.
This question points out the proverbial "dog that barked in the middle of the night." (If you need the context, it's from a Sherlock Holmes story, "Silver Blaze," in which the fact that a guard dog had not barked at an intruder was the significant clue.") The question is so obvious that it begs asking. Fully mobilizing the country, if in fact Iraq was the center of gravity in the war against terrorists, would have been completely justified. You might not think that "rogue nations" deserve civilized courtesies, but the US public certainly does. So, again, why no declaration of war?
I'll leave it up to you to answer this question for yourself for the time being. I have my own opinion, which I'll post later.