Historical clue formulations

• "___ in the Underworld" (Offenbach opera) — 2019-07-14
• The father of songs, according to Pindar — 2011-02-08
• Lover of Eurydice, in myth — 2006-06-11
• Traveler to Hades to rescue Eurydice — 2002-01-01
• Lover of Eurydice — 2000-01-06
• Stravinsky-Balanchine ballet — 1995-06-24