It is all too easy to take the all-volunteer armed forces for granted. They’ve been around now for 31 years, ever since the draft was abolished in 1973. We have become used to having a high-quality military filled by dedicated young women and men willing to put their lives on the line for less money than Donald Trump hands out in tips every week. It is worth remembering how extraordinary and unusual our service members really are – and how much we owe them this Thanksgiving.

The voluntarism tradition stretches far back in American history, all the way to the colonial militias, but it has never produced such a superb fighting force. For most of their history, the peacetime Army, Navy, and Marine Corps were laughingstocks that could not hope to compete with the world’s best. The entire armed forces in the 19th century usually numbered no more than 35,000 men – smaller than the New York Police Department today. Traditionally, they were so ill prepared that they wound up losing critical early battles from Bull Run (1861) to Kasserine Pass (1943).

To get a sense of the old military, read two novels written by veterans (and made into memorable movies] – Richard McKenna’s “The Sand Pebbles” and James Jones’s “From Here to Eternity.” Both were populated by misfits for whom the military was a welcome alternative to the penitentiary or the poorhouse.

The hegemony of the hard-bitten regulars ended in 1940, with the introduction of a draft that lasted until the end of the Vietnam War. In their post-Vietnam agony, all the services had trouble attracting recruits, and those who signed up tended to come from the bottom of the barrel – half were not even high school graduates. Low morale, racial tensions, and drug and alcohol abuse were rife in the 1970s.

By the 1991 Gulf War, those problems had evaporated and the first-rate military we know today had been created: A force whose enlisted ranks are composed of high school graduates and whose officers are college graduates (many with graduate degrees). A force where drug use has fallen into insignificance and morale and discipline are sky high. A force capable of knocking the stuffing out of just about any foe, anywhere in the world, at a moment’s notice.

Anybody who has spent any time around today’s soldiers, sailors, airmen, and Marines cannot help but be awed by their dedication, courage, and professionalism. Some anti-war protesters want to spread the idea that the military is composed of victims who have no alternative but to become cannon fodder. Nothing could be further from the truth, especially in front-line combat units where everyone is a volunteer twice over. Military personnel are actually better educated than the civilian population.

Why do they do it? Why have 1.5 million men and women enlisted in the active-duty military and another 861,000 in the National Guard and Reserves? The reasons vary, of course. Many are drawn by the prospect of learning a trade or earning a college scholarship. Others want an adventure or a sense of purpose. Once they spend some time in the service, the pull of camaraderie leads many to re-enlist.

But it would be a mistake to overlook the simplest and most obvious motive of all: sheer patriotism. People pull on their BDUs (battle dress uniforms) out of a desire to defend a great nation. Such sentiments can sound corny in today’s ironic culture, but the military is one place where old-fashioned pieties can still be uttered without a subversive smirk.

The all-volunteer force is now being tested as never before; it’s never had to fight a war as prolonged as the one in Iraq. The press naturally tends to focus on problems – small numbers of soldiers who refuse to obey orders or break the laws of war, reservists who fight recall to duty or complain about their hardships. This is to be expected. What’s amazing is not how many problems the military is experiencing but how few.

In spite of a punishing operations tempo and dismaying shortages of critical equipment like armored Humvees and the latest body armor, today’s GIs continue to soldier on with indomitable fortitude. They undertake incredibly difficult and dangerous assignments like the assault on Fallujah with less grumbling than the average commuter stuck in a traffic jam.

There is no way that civilian turkey-eaters can properly show our gratitude for those whose Thanksgiving meal comes in a chow hall thousands of miles from home. But for a start we can at least contribute to a number of charities that provide important aid to service members and their families. For a list, just go to www.defendamerica.mil and click on “Support Our Troops.”

Mr. Boot is a senior fellow at the Council on Foreign Relations and a columnist for the Los Angeles Times, where this first appeared.