In January 1900, Adolphus succeeded his father as Duke of Teck. The new Duke served with his regiment during the Boer War 1899–1900, for which he was promoted Brevet major in November 1900. He was later a transport officer in the Household Cavalry. In February 1904, he was promoted to the temporary rank of lieutenant-colonel and appointed a temporary military attaché at the British embassy in Vienna. His appointment as military attaché was confirmed in April 1906, and he received a staff posting the same month. He was promoted to the substantive rank of major in December 1906, and was raised to brevet lieutenant-colonel in November 1910.