What have we learned from 24 years of war? Since the First Gulf War in early 1991, the U.S. has had continuous combat operations in one theater or another. After the first war, combat air patrols enforced the No-Fly Zones over Iraq for years, until 9/11 triggered the first phase of the Afghanistan War and President Bush led the nation into the Second Iraqi War in March 2003.

Though this war officially ended with U.S. troop withdrawals in December 2011, the war continues to burn through lives and treasure in Iraq and it continues on in the memories, wounds and lives of veterans and their families.

What have we learned from 24 years of continual warfare? There may be two sets of answers: one set for policy-makers, those we have elected to make the consequential decisions of war and withdrawal, and another set for the citizenry who provide the volunteers who actually fight the wars and the treasure to pay for the wars and their long aftermath.

For policy-makers, Foreign Affairs just published three informed essays on the complex legacy of the Iraq/Afghanistan wars. Each is thoughtful and worth reading:

More Small Wars: Counterinsurgency Is Here to Stay by Max Boot

Pick Your Battles: Ending America's Era of Permanent War by Richard K. Betts

Withdrawal Symptoms: The Bungling of the Iraq Exit by Rick Brennan

I also recommend a previous Foreign Affairs article from 2005, just two years into the Second Iraqi War by former Defense Secretary Melvin Laird:

Iraq: Learning the Lessons of Vietnam

As for the citizenry, I would start with a few points I consider self-evident. I should note that ours is a military family, with service dating back to my grandfather's stint on the 4-stack U.S. Navy destroyer U.S.S. Lea which patrolled the western Pacific (with ports o' call in China) in 1920.

1. As a nation, we chose a professional volunteer military over a military of draftees in the 1970s. This has changed the nature of military service and reduced its role in civilian life. This has allowed our civilian leadership to send our military to war without directly affecting many civilian households. It renders war a distant abstraction for all who do not have active-duty family members.

2. As a nation, we have chosen to maintain a state of high readiness and overwhelming force as deterrents. This requires a large, permanent force and an equally permanent expense--though it should be noted that as a percentage of GDP, U.S. military spending continues to decline.

3. History suggests maintaining a hollow force with no real combat capabilities is a sure way to make bad decisions and suffer horrendous losses. Hollowing out the nation's military doesn't mean war is any less likely; it just means the losses suffered by those serving will be much higher should war come.

4. There is no substitute for combat operations in terms of experience and lessons learned. That said, the lessons are wasted unless they are absorbed by the entire bureaucracy of war-fighting and the civilian leadership that makes the decisions of war and withdrawal.

What have our military and civilian leaders learned from 24 years of war? Hopefully the lessons are as complex and nuanced as the wars.

We should treasure and retain the mid-rank officers and combat veterans we have in uniform. Any nation that has not engaged in combat in decades would be foolish indeed to take on a military with decades of combat operational experience. That is deterrence we would not choose but now that we have it, it should not be squandered.

5. War is not abstract; it it fought by individuals. We should be careful about tossing around abstractions such as 420,000 active-duty soldiers or our overseas commitments that end up falsifying the reality that sending forces into harm's way is sending individuals into harm's way. Reducing messy reality to a clean abstraction is a sure way to lose one's way.

6. Simplistic ideologies such as neo-conservativism (neo-con) lead to ill-informed civilian leadership decisions.

7. Wars are easier to start than to end.

8. We increasingly demand the impossible of our military: every decision is examined with the infinite luxury of hindsight by critics with no combat or military experience, every action is expected to unfold as flawlessly as a Hollywood war sequence, and the military is supposed to perform non-combat duties such as nation-building, despite a paucity of resources and training.

9. Our civilian leadership's ignorance of other cultures, their histories and the limits of war have led to catastrophically high levels of hubris and over-confidence.

10. War is not diplomacy, nor is it nation-building. Confusing the three wastes our military forces on futile no-win quagmires.

11. It's easier to disrupt an enemy's networks of communications and logistics than to defend one's own long supply chains.

12. Wars without clear tactical and strategic goals that are achievable with military force cannot be "won" and should never be started.

13. The world is not a suburb of Washington, D.C. and its inhabitants do not respond like policy-makers' suburban neighbors.

14. The responsibility for starting and ending wars, the way wars are fought and the losses we suffer all rest with our elected civilian leadership.