Loose Lips

During the Civil War, how did a general know the size of the opposing force?

McClellan had on hand Alan Pinkerton, of the well-known Pinkerton Detective Agency, to do his snooping for him. Unfortunately, whether through incompetence, indifference or ill-will, Pinkerton frequently overestimated Confederate numbers, to which McClellan would add a hefty ten, fifty, or a hundred percent, usually to obtain more men or supplies, but more often than not, to provide a cover to justify his own procrastination.

In May of 1863, facing the Army of the Potomac under a new commander, Joseph Hooker, Lee found an ingenious way to gauge to size of his re-tooled foes. Both sides had spies everywhere, and Lee was sent a Union newspaper article containing an interview with Hooker’s medical director. The director is quoted as stating that the Army of the Potomac currently had 10,777 men on the sick roster. A few sentences later, this same man in this same journal goes on to extrapolate that this number amounted to 67.64 men per 1,000.

The rest is simple math, which Lee did:

67.64 / 1,000 = 10,777 / x

Cross-multiplication yields

67.64 x = 10,777,000

Divide both sides by 67.64 and one gets

10,777,000 / 67.64 = x = 159,329

So Lee concluded from this newspaper report that he was facing 159,329 federal soldiers. (Which was pretty close to the truth. Officially, Hooker was marching with 163,000 men, but this number included teamsters, cooks, horse wranglers, etc.) This bit of intel helped Lee develop a strategy so that his meager force of 58,800 would completely route Hooker in the Battle of Chancellorsville a few days later.

Too bad the phrase “loose lips sink ships,” and the idea behind it, did not become popular until World War II seventy-five years later …