What day of the week was July 20, 1866?

The day of the week July 20th, 1866 fell on was a Friday.

Bernhard Riemann the German mathematician and academic (b. 1826) died on this day in 1866.

Austro-Prussian War: Battle of Lissa The Austrian Navy the led by Admiral Wilhelm von Tegetthoff, defeats the Italian Navy near the island of Vis in the Adriatic Sea.