Nevertheless, in the following years, chemical weapons were used in several, mainly colonial, wars where one side had an advantage in equipment over the other. The British used poison gas, possibly adamsite, against Russian revolutionary troops beginning on 27 August 1919 and contemplated using chemical weapons against Iraqi insurgents in the 1920s; Bolshevik troops used poison gas to suppress the Tambov Rebellion in 1920, Spain used chemical weapons in Morocco against Rif tribesmen throughout the 1920s and Italy used mustard gas in Libya in 1930 and again during its invasion of Ethiopia in 1936. In 1925, a Chinese warlord, Zhang Zuolin, contracted a German company to build him a mustard gas plant in Shenyang, which was completed in 1927.