Lord Palmerston? Apocryphal?
Dear Quote Investigator: There is an anecdote about a fiendishly complex diplomatic agreement. Negotiating, signing, and comprehending the pact had sent one person to the grave, sent a second to a lunatic asylum, and left a third with memory loss. Are you familiar with this tale?
Quote Investigator: This story is based on a remark ascribed to British statesman Lord Palmerston who died in 1865 about the intricate Schleswig-Holstein Question.
The earliest match located by QI appeared in an 1873 Italian book about political and military events in 1866 titled “Un Po’ Più Di Luce Sugli Eventi Politici E Militari Dell’ Anno 1866” by Alfonso La Marmora. Here is an Italian passage followed by an English translation. Emphasis added to excerpts by QI: 1
La questione danese, o per meglio dire dello Schleswig-Holstein era talmente complicata e oscura che Lord Palmerston non essendo riuscito diplomaticamente a impedire quella guerra, soleva spiritosamente raccontare, che tre soli individui conoscevano a fondo quella imbrogliata controversia. Uno era il principe Alberto, che disgraziatamente era morto; il secondo un uomo di Stato danese, che era impazzito; il terzo lui, Lord Palmerston, che l’aveva dimenticata.
The Danish question, or better put that of Schleswig-Holstein, was so utterly complicated and obscure that Lord Palmerston, not having been successful in preventing that war through diplomacy, used to quip that only three individuals knew the cause of the tangled dispute. One was Prince Albert, who unfortunately was dead; the second was a Danish official who had gone mad; and the third was he himself, Lord Palmerston, who had forgotten it.
Below are additional selected citations in chronological order.