Nils Otto Tank
Otto Tank was born at Rød Herregård, the family estate near Halden, in Østfold county, Norway. The son of a wealthy politician and landowner, Tank was educated in various European universities. His father Carsten Tank (1766–1832) had been Minister of Finance on the governing council in Norway in 1814. His mother, Cathrine von Cappelen Tank (1772–1837) was the daughter of Diderich von Cappelen, a wealthy land-owner and ship owner. In 1813 Tank was sent to a school in Oslo and in 1818 to a Moravian School in England. In 1834, he was sent to serve at the Moravian settlement in Christiansfeld, Denmark.
In 1842, Tank and his wife left to become teachers and missionaries in the Dutch colony of Suriname. During that time, his daughter was born and his wife died. Tank's experience in Suriname ended on a bitter note. In colony such as Suriname, the economy depended upon slaves for the labor-intensive plantations of sugar cane, timber, coffee and other tropical products. It became increasingly clear to Tank that the treatment of the slaves in Suriname was intolerable. In 1847, he asked to be relieved of his duties in Suriname and returned to Europe. 
In 1850 the family migrated to the United States. The Tanks traveled to Wisconsin near Green Bay where a group of Norwegian Moravian immigrants wished to form a settlement. Tank purchased a tract on the west bank of the Fox River at Fort Howard, including the historic Tank Cottage. Tank planned to establish a communal society. However, the religious community elected to settle elsewhere.
Tank became associated with the Fox-Wisconsin River Improvement Company, but eventually lost heavily in the venture. He then turned his promotional activities to land speculations in Menasha and Manitowoc, and to railroad ventures, chiefly the Green Bay and Minnesota Rail Road.
His first wife, Marianne Dorothea Frueauf (1804–1844) was born in Grosshennersdorf near Herrnhut. Otto Tank and Marianne Frueauf were married in Herrnhut during 1838. Their daughter Marianna Fredericka was born in Suriname in 1843. His second wife, Caroline Louise Albertina van der Meulen, (1803–1891) was born in Amsterdam, Netherlands. In 1849, Otto Tank married Caroline van der Meulen who lived on wealth inherited from her own family.
After the death of Nils Tank in 1864, Caroline Tank remained in Fort Howard until her death in 1891. In 1867, she donated books to the State Historical Society of Wisconsin, later transferred to the University of Wisconsin in Madison. Caroline donated land to build a Home for Children of Foreign Missionaries in Oberlin, Ohio; the building is now known as Tank House and serves as a residential co-operative for students at Oberlin College. She donated park land to the City of Green Bay. She gave money to several missions in China as well as to American schools. In 1867 she donated a large collection of Dutch-language books to the Wisconsin State Historical Society.
The Tank Cottage at Heritage Hill State Historic Park in Green Bay is reported to be the oldest house in Wisconsin. It was located on the west bank of the Fox River. In 1850 Otto Tank bought the building and added both wings to the house. In 1975 the building came down the river on a barge and became a part of Heritage Hill State Historical Park. The building is listed on the National Register of Historic Places (added 1970 - Building - #70000028).
- Nils Otto Tank: Norwegian Aristocrat and Philanthropist (William A Titus. Antes Press. 1939)
- Niels Otto Tank, Moravian Missionary To Suriname And Wisconsin (Transactions of the Moravian Historical Society, Vol 29, 85-102. 1996)
- Getting organized in Milwaukee (The West Side Moravian Church)
- Fox and Wisconsin River Improvement Company (Dictionary of Wisconsin History)
- Nils Otto Tank (Dictionary of Wisconsin History)
- Tank Cottage (Heritage Hill State Historical Park)
- Tank Cottage.2640 South Webster Avenue, Green Bay (National Register of Historical Places)
- Holand, Hjalmar Rued Nils Otto Tank (The Society. 1909)
- Titus, William A. History of The Fox River Valley Lake Winnebago and The Green Bay Region, Volume II (Chicago: S.J. Clarke Publishing Co. 1930)