On today’s date in 1938, a new opera by the 74-year-old German composer Richard Strauss had its premiere at the Munich National Theater. It was entitled “Friedenstag” or “Peace Day” —a rather ironic title, considering a Second World War was imminent.

The idea for the opera came from the Austrian writer Stefan Zweig, who was a pacifist, and, as an Austrian Jew, persona non grata in Nazi Germany. Strauss had landed himself in hot water for wanting to work with Zweig despite the Nazi Race Laws, and so “Peace Day’s” libretto was written by another Austrian, Josef Gregor, a writer Zweig had himself suggested as an “acceptably Ayran” replacement.

The opera’s story takes place during the Thirty Years War in 17th century Germany. The military commander of a besieged town decides to blow the whole place up rather than surrender, and is about to do so when he misinterprets a signal and opens the gates, allowing a peaceful takeover. The surprised commander is reconciled to his enemy, and everyone celebrates their deliverance from the horrors of war.

Hitler did not attend the Munich premiere, and supposedly thought the historical peace following the Thirty Years War a disaster for Germany. But the opera could be interpreted many ways, and, after the “peaceful” takeover of Austria by Nazi Germany, Hitler did in fact attend the Viennese premiere of “Peace Day” in 1939. The new opera played in other German opera houses briefly, but after the outbreak of war was quickly dropped.

And to this day, depending on whom you ask, Strauss’ ambiguous opera is either a work celebrating peace—or appeasement.