America is exchanging prisoners with the enemy! It’s an outrage! That’s been a constant refrain of GOP critics since President Obama traded five Guantánamo Bay captives for U.S. soldier Bowe Bergdahl, who was released by the Taliban on May 31. But the most basic history lesson reveals that there’s really nothing new — or outrageous — about wartime prisoner exchange, as Bergdahl’s own Republican congressman has acknowledged.

“If you look historically, at the end of any conflict, you have a swap of prisoners,” Rep. Raul Labrador, R-Idaho, told a local radio station last week. “So I would suggest that anybody who’s being hyper-critical about this, they should look at the history. This has happened before.”

He’s right. Prisoner exchange dates to the founding of the United States, when Americans traded war captives with their British foes. And it has persisted since then, for a very good reason: It’s humane. On the cruel and brutal sea of war, prison exchange remains a beacon of compassion and benevolence.

Let’s look at the history. During the War of Independence, thousands of Americans languished in filthy British prison ships. American Gen. George Washington corresponded frequently with his British counterpart, Gen. Lord William Howe, to liberate as many prisoners as possible...