“Pour encourager les autres”

Running around the track tonight, I found myself musing over the famous ironic expression by Voltaire in Candide: “pour encourager les autres.”  The more I thought about it, the less convinced I was that I understood it, in the sense of being able to come up with cleverly parallel situations in which the irony of the expression is preserved.  I would be interested to know how one would explain the ironic function in the phrase as used in Candide.

The phrase is found in the famous (and actually historical) scene of the execution of a British admiral, John Byng, on the deck of his own ship, for allegedly failing to engage the enemy in the Battle of Minorca.  Voltaire adds of this:

Dans ce pays-ci, il est bon de tuer de temps en temps un amiral pour encourager les autres.” (“In this country, it is wise to kill an admiral from time to time so to encourage the others.”)

The un-ironic meaning could be preserved by simply saying “incentivize” or “motivate” the others.  Similarly “threaten” or even “discourage” the others from failure.  The irony is given by deliberately using “encourage.”  Explain this, however, and give me some parallels in modern life where that precise irony is preserved.  At least when I was operating on 20% oxygen going around the track, I found it harder to think up exactly ironic parallels than I would have thought.  (And if the Language Log wanted to weigh in, so much the better!)