#OnThisDay, 12 May 1743, Maria Theresa Habsburg is crowned Queen of Bohemia and consolidates her position as the ruler of the Austrian empire. The Seven Year War was promoted by rival claims to the empire, and she worked to elevate her husband to be Holy Roman Emperor. After his death she co-ruled with her son.
She sponsored trials of smallpox inoculation, having lost three of her children to the disease.
#OnThisDay, 15 Jan 1559, Elizabeth Tudor is crowned as Queen Elizabeth of England. She reigned alone until her death in 1603. Her foreign policy included privateering, colonising Virginia and approving the start of the East India Company.
#OnThisDay, 11 Jan 1055, Theodora Porphyrogenita is proclaimed sole 'emperor' of the Byzantine Empire after the death of her sister Zoë. The sisters had previously ruled the empire - the most powerful economic, cultural, and military force in Europe - together.