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Early political career

As Leopold's older brother, the earlier crown prince Louis Philippe, had died the year before Leopold's birth, Leopold was heir to the throne from his birth. When he was 9 years old, Leopold received the title of Duke of Brabant, and was appointed a sub-lieutenant in the army. He served in the army until his accession in 1865, by which time he had reached the rank of lieutenant-general.

Leopold's public career began on his attaining the age of majority in 1855, when he became a member of the Belgian Senate. He took an active interest in the senate, especially in matters concerning the development of Belgium and its trade, and began to urge Belgium's acquisition of colonies. Leopold traveled abroad extensively from 1854 to 1865, visiting India, China, Egypt, and the countries on the Mediterranean coast of Africa. His father died on 10 December 1865, and Leopold took the oath of office on 17 December, at the age of 30. He also served in the Belgian Senate during this time.