By the outbreak of the First World War Frederick William Leist was an expatriate living and working in London as an illustrator for the Graphic. During the war Leist initially worked for the British War Office and H.M. Stationery Office designing recruitment posters from 1915-1916. Then, in 1917, he became one of ten Australian artists living in Britain to be appointed official war artists. Leist was attached to the 5th Division Australian Imperial Force (AIF) as an honorary lieutenant from 3 September 1917 until 31 March 1920. He was at the Western Front from September to December 1917 and again from June to August 1918, this time working alongside fellow artist A. Henry Fullwood. His skill as a draughtsman and ability to work quickly 'en plein air' ensured that collectively his drawings, watercolours and small oil paintings give an insightful impression of life at the front line for Australian soldiers, the Belgium and French civilians living alongside them and the battle ravaged landscape itself.
Leist's work was included in Australia in The War, an exhibition of paintings and photographs by Australian war artists at the Grafton Gallery, London, 25 May - 22 June 1918. Other exhibiting artists included Charles Bryant, George Lambert, Frank Crozier, H. Septimus Power and James Quinn. Leist also designed the lithographic poster used to promote the exhibition. Between the war's end and 1921 he was commissioned by the Australian War Records Office to produce several large paintings depicting key moments in the third battle of Ypres and the capture of Mount St Quentin. He was further commissioned in 1927 by Australian War Records to paint the sinking of HMT Southland.
In the late 1880s Leist studied art at Sydney Technical College and at the Art Society of NSW while training as a furniture designer in the workshops of David Jones. At the Art Society of NSW Julian Ashton conducted classes and this is where Leist was introduced to plein air painting. During the 1890s he worked as an illustrator for the Bulletin and Sydney Mail and established his reputation as a black & white artist.
After his war service he painted two large murals for the Australian Pavilion at the British Empire Exhibition held at Wembley in 1924. As a result of these works Leist gained several commissions from the United States and toured the south-west before returning to Australia in 1926. In 1929 Leist became the Head of Painting at East Sydney Technical College and remained so until 1938. He was a member of the Royal Art Society of NSW and the Australian Watercolour Institute. His work is represented in the collections of state and regional public galleries including the National Gallery of Australia and the Art Gallery of NSW. Leist died in Sydney, February 1945, and was survived by his wife Ada and a daughter.