Maria Theresia

Listening to Hadyn's Symphony No. 48 in C Major "Maria Theresia".

I was wondering who Maria Theresia was, after whom such a beautiful symphony was named. Perhaps this is worth some efforts of digging in the library:

Maria Theresa (1717-1780), the eldest daughter of Charles VI, who promulgated the Pragmatic Sanction to permit her to suceed to the Habsburg monarchy and Elisabether Christine of Brunswick-Wolfenbuettel, was Archduchess of Austria and Queen of Hungary and Bohemia and, through her marriage, Holy Roman Empress.