Wendt was born in
Itzehoe, a small town in
Holstein, then a Danish province, son of Joachim Matthias Wendt and his wife Christina, née Schlichting. After his mother's death around 1839 he was brought up by his father and two sisters, then apprenticed to a watchmaker and silversmith. and was
naturalised as a British citizen in 1864, facts which he used to deflect the popular ill-feeling against people of German origin during the
Great War. He began business as watchmaker and jeweller in the City of Adelaide at Pirie Street, and in 1852 opened premises at 68 Rundle Street, moving to larger premises at 84 Rundle Street in 1861 then no. 70 in 1874. Julius Ludwig Schomburgk (ca.1818 – 9 March 1893), a brother of
Moritz Richard Schomburgk, was for many years Wendt's principal designer and workshop foreman. His business expanded steadily until it became one of the largest and best known in Australia. In 1869 he opened another shop at
Mount Gambier and in 1888 another in
Broken Hill, New South Wales, though this business was sold around 1895.
Later development ) In 1903 his son Julius M. "Jule" Wendt and stepson Hermann Koeppen-Wendt were brought in as partners in the firm and took over its management. Jule moved to London leaving Hermann in charge of the Adelaide business. When J. M. Wendt senior died in 1917, Hermann Koeppen-Wendt inherited the business. His sons A. and Kenneth were fighting overseas; Kenneth was killed in France and in 1927 Alan was brought into the company as an equal partner with his father, • He built the Freemasons' Hall in Flinders Street • He was a member of the Tintinara Land Syndicate, which is credited with the discovery that the so-called 90-mile desert is not a barren waste, but by treatment with
trace elements could become valuable arable land. • He invested in gold mines in South Australia, notably the
Bird-in-Hand and Mount Torrens. • In later years he studied
Count Mattei's system of homoeopathy, and treated many people. ==Recognition and notable work==