I was busy Memorial Day with my family, culminating in the traditional hamburger dinner. But all the while I was haunted by the images I have seen in the past few years visiting America’s immaculately maintained military cemeteries — not only Arlington National Cemetery but also its overseas offspring in, inter alia, Tunisia, Manila, and Normandy. All are spare and beautiful, fitting monuments to the men and women who fell so that we may be free. So many crosses, along with some Stars of David — so much pain, so much sacrifice, so much heroism and in so many places. It’s hard to comprehend fully when you are a coddled civilian living in the luxury that these fighting men made possible.

The question is: What do we owe this long line of defenders, living and dead, including the two million veterans of our ongoing conflicts in Afghanistan and Iraq? Respect, obviously, along with all of the financial and other benefits that it is in our power to bestow. But does our obligation extend beyond the obligatory words, “Thank you for your service”?

Bing West, a Marine veteran of the Vietnam War, and his son Owen West, a Marine veteran of the Iraq War, argue: “A social contract exists between those who go into battle and those who send them there. The vast majority of our fatalities occur in the Army, Marine and Special Forces units that serve on the ground — our grunts. A grunt fights with all his might to win. Similarly, policymakers, elected officials, and generals must fight with all their might to provide him attainable goals and the resources to win. If they falter in their resolve — or worse, if they just plain quit on the fight — they have broken the social contract.”

The Wests argue that this social contract has been broken in Iraq and Afghanistan: “In Afghanistan and Iraq, President George W. Bush and the generals intended to build democratic nations. They set unattainable goals. President Obama plain quit by withdrawing forces completely from Iraq and leaving only a token force in Afghanistan.”

You can argue about the specifics; I think that the goals President Bush set in Iraq and Afghanistan were not so unobtainable — in fact, in Iraq, we had largely obtained our goals before President Obama’s ill-advised pullout. But the larger message is hard to quarrel with: The larger American society has not shown the same will to win as that displayed by our grunts who have risked life and limb to destroy our enemies.

This is not, of course, a new phenomenon. The most notorious past example of faltering occurred in Vietnam where, after the loss of 58,000 troops, President Nixon and Congress withdrew all of our forces and later stood by as South Vietnam was conquered by the North.

World War I was another betrayal of trust. More than 116,000 U.S. troops perished in that conflict only to have the U.S. pull out of Europe immediately afterward, allowing Nazis and fascists to come to power and setting the stage for another world war — one that would consume 400,000 American lives.

To some extent even the commitment of the Civil War — which cost more than 700,000 lives on both sides — was not fully redeemed. True, the Union was preserved and the Confederacy was destroyed, along with slavery. But the North did not fully complete the project of Reconstruction. As a result, slavery was replaced by the vile Jim Crow laws that made a mockery of the 14th, 15th, and 16th Amendments to the Constitution passed in the war’s aftermath to guarantee civil rights for all.

What do all these betrayals of trust have in common? A failure by the American population and politicians to sustain a long-term commitment that would build on battlefield gains.

If U.S. troops had remained in the South after 1876, the reign of terror by the Ku Klux Klan against freedmen and their Northern defenders (derided as “carpetbaggers”) might not have succeeded, and segregation might have been avoided. If U.S. troops had remained in Europe after 1918 to enforce the peace, there might have been no Nazi aggression. If U.S. troops had stayed in South Vietnam after 1973, that nation might still exist. And if U.S. troops had stayed in Iraq after 2011, ISIS might never have created an Islamic State.

There is also, of course, the possibility that if U.S. troops had stuck around, they might have suffered casualties, although in the South, Vietnam, and Iraq casualties had been reduced to close to nothing by the time U.S. forces pulled out. But at the very least a prolonged U.S. commitment, manned by volunteers, could have allowed those who were willing and able to fight to see through the commitments that brought America into those conflicts in the first place.

But the troops never had the chance to win because the politicians pulled the plug. Oddly those who suffered and risked the most were generally the most willing to stay the course while leaders and civilians safe on the home front were eager to pull out — in no small part because of guilt over the risks borne by others.

There is no way to eliminate the risk of such betrayals in the future. But we should bear them in mind when making troop commitments in the future. If there is a great risk that the politicians and the public will not sustain a military commitment over the long run, it is often better that it should not be made to begin with. And if the U.S. does send its troops into harm’s way, it should give them the tools and the support to finish the job, however long that will take.