Hmmm…I see a few candidates, but these stick out to me:
>AD 70 – Siege of Jerusalem: Titus, son of emperor Vespasian, opens a full-scale assault on Jerusalem and attacks the city's Third Wall to the northwest.
>1941 – World War II: Rudolf Hess parachutes into Scotland to try to negotiate a peace deal between the United Kingdom and Nazi Germany.
https://en.wikipedia.org/wiki/May_10