King George I was the emperor of Greece from 1863 to 1913. He was born in the mid-1840s in Denmark as Prince William of Schleswig-Holstein-Sonderburg-Glücksburg, a junior branch of the House of Oldenburg, which had been ruling Denmark since 1448. Although initially destined for a career in the Danish Royal Navy, he was elected the King of the Hellenes by the Greek assembly at the age of 17, after which he moved to Athens. From the very beginning, he was very conscious about his position; therefore, he quickly learned Greek. He also mingled freely with his subjects and eventually sent back his Danish advisors so that his people did not feel that he was too influenced by them. His long reign was characterized by the institution of universal male suffrage and unicameral legislature in Greece. It was also during his reign that Greece began to expand territorially, with Great Britain ceding Ionian Islands peacefully. Later, Thessaly and Macedonia were also annexed. King George I was assassinated possibly by a mad man just before the completion of his 50 years of reign.