Johann Friedrich Wilhelm Baucke, known as William, was born on Chatham Island on 7 July 1848. He was the second of nine children of Johann Heinrich Christoph Baucke and his wife, Maria Müller. Baucke's father was one of a group of German Lutheran missionaries who had come to New Zealand in 1843, and shortly afterwards moved to the Chatham Islands. Maria Müller was sent out by the same mission society in 1846.
William and the other mission children were taught by Maria in a class open also to Māori and Moriori children. It is possible that William, when he was old enough, gave a hand with the younger children. Outside the classroom he was encouraged by his father to mix with the local people and learn their language, customs and traditions, provided this did not mean dodging Scripture lessons or work on the property.
In 1862 Baucke was sent to school in Wellington. He later returned to the Chathams, where he became schoolmaster to both native and Pakeha children. Baucke seems to have taught himself French, Italian and Greek; he already spoke German, English, Māori and Moriori. About this time the family fortunes changed. Maria Baucke died in 1866, and at some point the family farming operations failed. Perhaps for this reason, Johann Baucke's plan of placing William in the South Seas mission lapsed.
William Baucke's activities over the next 30 years are not clear. He claimed to have fought with Gustavus von Tempsky's Forest Rangers in the late 1860s and to have received a leg wound; his brother scornfully claimed that this had been accidentally inflicted by an axe. He married Catherine Eliza Hughes at Wellington on 13 July 1870; they had at least two sons. In the 1880s he worked on Edward Chudleigh's farm at Wharekauri, Chatham Island, and built a house and stables on the property.
It is not certain when Baucke moved permanently to the mainland. He is said to have had, for a time, a business running vessels between the islands and New Zealand. He was at Glentunnel, Canterbury, in 1903, but moved to the King Country and had settled in Te Kūiti by 1906, where he worked as a licensed interpreter. By 1914 he had moved to Otorohanga, where he is variously recorded as a journalist, builder and farmer. Baucke immersed himself in Māori village life in the King Country and became a passionate champion of a people he saw as losers in a clash of cultures. Towards the end of his life he seems to have adopted a young Māori girl, Teruteru. His interest in the Greek classics persisted until his death, and he found solace in playing the violin and singing.
Baucke was best known in his lifetime for his series of tales and articles on Māori life and customs written for the New Zealand Herald and the Auckland Weekly News. This material was collected in 1905 as 'Where the white man treads'; the book was republished in a slightly different form in 1928. In the same year, The Morioris, a monograph by H. D. Skinner with additional material by Baucke, was published. Baucke's unflattering portrayal of the Moriori takes no account of the fact that he knew them only after they had been thoroughly demoralised by invasion and slavery. Skinner and Alexander Shand, who had also lived on the Chathams when Baucke was there, took issue with his negative portrayal; Baucke never spoke to Shand again. Skinner, however, regarded his work, for all its limitations, as 'an important contribution to Moriori ethnology, especially on the linguistic side'. He was reputed to be the last living man to have direct knowledge of the Moriori language. He died at Otorohanga on 6 June 1931, survived by his wife and two sons.
William Baucke's life, varied though it was, may have been less romantic than he implied in some of his writings. Nevertheless, his upbringing had given him the strength of character to rise above difficult circumstances. He was eventually able to use his education and his background to advantage in preserving his knowledge of a vanished language and culture.