He joined the Army of Guinea in 1990 as a corporal and was later appointed as the Chief of Fuels at the Guinean army base in Kindia, about 60 miles northeast of Conakry. From 2001 to 2002, Dadis was sent to Sierra Leone as a member of the United Nations' peacekeeping troops. In 2004, President Conté sent Dadis, along with several other Guinean Soldiers, to Bremen, Germany, for 18 months’ military training. In November 2008, he was named head of the Guinean army's fuel supplies unit, a branch of the Guinean Minister of Defense's cabinet. He was one of the leading mutineers in the 2008 Guinean military unrest. Prior to the December 2008 coup, he was not well known by the general population.