If you were a member of the European nobility, the summer of 1798 was a scary time. That revolutionary wild man Napoleon Bonaparte had crushed your armies on land and now word had it his fleet had escaped a British blockade. The possibility that Napoleon would control both land and sea struck terror in many a nobleman’s breast.

During this anxious time Prince Nicholas Esterhazy the Second’s favorite composer Joseph Haydn composed a Latin mass titled “Missa in angustiis” or “Mass in Time of Fear.” It opens in the key of d minor, the key employed by Mozart for the spookiest scenes in “Don Giovanni,” an opera that had made a big impression on Haydn at its premiere in Vienna ten years earlier. As Haydn scholar H. C. Robbins Landon puts it, in ‘Don Giovanni,’ 18th century listeners were presented with "the presence of real fear — nay terror.”

So, when word reached the rattled princes of Europe that the British Admiral Nelson had destroyed the French fleet, everyone breathed a huge sigh of relief, and, coincidentally, Haydn ends his Mass in the more optimistic key of D Major.

First performed on today’s date in 1798, Haydn’s work soon came to be known as the “Lord Nelson Mass,” and in Robbins Landon’s view stands as “arguably Haydn’s greatest single composition.”