There’s no doubt that Vietnam was quantified in new ways. McNamara had brought what a historian called “computer-based quantitative business-analysis techniques” that “offered new and ingenious procedures for the collection, manipulation, and analysis of military data.”

In practice, this meant creating vast amounts of data, which had to be sent to computing centers and entered on punch cards. One massive program was the Hamlet Evaluation System, which sought to quantify how the American program of “pacification” was proceeding by surveying 12,000 villages in the Vietnamese countryside. “Every month, the HES produced approximately 90,000 pages of data and reports,” a RAND report found. “This means that over the course of just four of the years in which the system was fully functional, it produced more than 4.3 million pages of information.”

Once a baseline was established, decision makers could see progress. And they wanted to see progress, which created pressure on data gatherers to paint a rosy picture of the portrait on the ground. The slippage between reality and the model of reality based on data became one of the key themes of the war.

“The crucial factors were always the intentions of Hanoi, the will of the Viet Cong, the state of South Vietnamese politics, and the loyalties of the peasants. Not only were we deeply ignorant of these factors, but because they could never be reduced to charts and calculations, no serious effort was made to explore them,” wrote Richard N. Goodwin, a speechwriter for Presidents Kennedy and Johnson. “No expert on Vietnamese culture sat at the conference table. Intoxicated by charts and computers, the Pentagon and war games, we have been publicly relying on and calculating the incalculable.”

All of which the “apocryphal story” condenses into a biting joke.

But was there actually a computer somewhere in the Pentagon that was cranking out “When will we win the war?” calculations?

On October 27, 1967, The Wall Street Journal ran an un-bylined blurb from its Washington, D.C., bureau on the front page talking about a “victory index.”

U.S. strategists seek a “victory index” to measure progress in the Vietnam War. They want a single statistic reflecting enemy infiltration, casualties, recruiting, hamlets pacified, roads cleared. Top U.S. intelligence officials, in a recent secret huddle, couldn’t work out an index; they get orders to keep trying.

Now, a victory index is not quite a computer program you can ask “When will we win the war?” But it’s pretty close! A chart could be plotted. Projections could be made from current progress to future ultimate success. At the very least, we can say that officials tried to build a system that could be the kernel of truth at the center of a certainly embellished story.