Military leaders determine how and where to fight wars not if and when to fight them. The reason is obvious: Warfare is the culmination of a military career.

It is only common sense to acknowledge that someone who has spent his entire career studying and practicing the art of war would one day wish to put those skills to the task.

Without a war, a general is a conductor without an orchestra, a doctor without a patient, a lawyer without a case. Where is the fulfillment if the skills acquired are never tested?

For this reason political leaders should be wary of the views of military advisers. War not only provides them with the opportunity to demonstrate their competence, but it also elevates their importance and provides opportunities for advancement and recognition.

War often becomes its own justification as the reasons for the conflict diminish with the investment of blood and treasure. Regardless of its merits, the conflict must continue and “victory” achieved; otherwise the sacrifices have all been in vain.

Senator John McCain’s strong support for the wars in Iraq and Afghanistan has been shaped by his experience in Vietnam. That war was lost not because it was a mistake, but because we failed to persevere, thereby dishonoring those who fought and died there.

Getting into a war is far more difficult than getting out. It’s like someone continuing to pay the mortgage on a bad real estate investment in the hope the market will turn around. It’s one thing to cut your losses when the investment is only money but another when it involves the death and disabling injuries of those who answered the call.

The “light at the end of the tunnel” in Vietnam has become “turning the corner” in Afghanistan. The decision-makers struggle to come up with some resolution they can call a “victory.”

Deposing Saddam Hussein and the establishment of a “democratic” government became Iraq’s “victory.” This, despite how fragile that government remains and its close ties to Iran, our principal adversary in the Middle East.

Afghanistan’s “victory” will likely involve an agreement with the Taliban that will permit us to withdraw our troops honorably.

A successful outcome of our nation- building efforts is doubtful. I expect that in neither country will our investment be worth the price we have paid, not to mention, the loss of life suffered by the inhabitants.

Generals form a bond with the men and women they command. That emotional tie and their professional reputations make it almost impossible for them to admit to a mistake.

To have sent brave soldiers to die in vain is a terrible burden. Is it any wonder that military leaders will cling to a justification for that sacrifice long after others see only folly?

Although well intentioned and sincere, the advice of commanders must be seen within the context of their roles and their commitment to their troops, living and dead.

James W. Dolan is a retired Dorchester District Court judge who now practices law.