Sidenberg was born in
Trachenberg, near
Breslau, in
Silesia, which was then part of the kingdom of
Prussia. He was the first son of Wilhelm Sidenberg (16 April 1782 – 15 May 1817) and Henriette Bruck Sidenberg (16 September 1815 – 18 May 1896). On 14 September 1854, he arrived in New York City on the ship
Elizabeth with his mother, three younger brothers, a sister, and perhaps other relatives; his father seems to have traveled to the United States separately. The family first went to
New Bedford, Massachusetts, and then moved to
Missouri where Wilhelm worked as a
peddler. With the outbreak of the
American Civil War, the Sidenberg family moved to New York City. By 1863, Sidenberg was in business with his father as G. Sidenberg and Company; his brothers Henry Sidenberg and Richard Sidenberg shared the same business address and their families were frequently associated with Gustavus in this business. The firm was a manufacturer and importer of
collars and
cuffs, specializing in ladies
linen and
lace collars, cuffs,
rufflings,
veils, and
sleeves. On 26 June 1866, in New York City, Sidenberg married Theresa Goldsmith (22 April 1848 – 19 February 1910). For the remainder of the nineteenth century, the firm of G. Sidenberg and Company continued, at various
Manhattan addresses, and did an extensive business in both the manufacture and
importation of lace goods. They advertised heavily and employed
traveling salesmen throughout the United States. In 1898, Sidenberg left the family firm and purchased a seat on the
New York Stock Exchange. Doing business as Sidenberg and Kraus,
brokers, they specialized in purchase and sale of
bonds. In 1892, he built a
steam yacht, which had been designed by the noted marine
architect Henry I Gielow and constructed at the yard of C.R. Poillon in
Brooklyn. He named the yacht
Theresa, and became a regular in New York boating circles. Sidenberg was also a patron of the
Metropolitan Opera and of a number of
Jewish charities. After the death of his first wife in 1910, he married Therese, or Theresa, Wertheimer Gumbinner (22 March 1858 - ?). On 22 January 1915, Sidenberg died at his home at 40 W. 56th Street in New York City. He had no children. His estate was divided among several charities and the families of his brothers and sisters. ==Hotel Theresa==