When was the Russian dramatist who wrote The libretto born?
Iolanta:  The libretto was written by the composer's brother Modest Tchaikovsky, and is based on the Danish play "Kong Renés Datter " ("King René's Daughter") by Henrik Hertz, a romanticised account of the life of Yolande de Bar. Modest Ilyich Tchaikovsky: Modest Ilyich Tchaikovsky (Russian: Моде́ст Ильи́ч Чайко́вский ; 13 May [O.S. 1 May] 1850 –15 January [O.S. 2 January] 1916 ) was a Russian dramatist, opera librettist and translator.
13 May [O.S. 1 May]