Under French colonial administration, in 1921 they contracted Société de Construction des Batignolles to construct the railway using forced labour, recruited from what is now southern Chad and the Central African Republic. Like Spain and Portugal, France did not ratify the International Labour Organization Forced Labour Convention of 1930, No. 29. Disdain among the native population towards this conscripted labour and other forms of oppression led to the Kongo-Wara rebellion between 1928 and 1931. Through the period of construction until 1934 there was a continual heavy cost in human lives, with total deaths estimated in excess of 17,000 of the construction workers, from a combination of both industrial accidents and diseases including malaria. In 1946, France ratified ILO No.29, in light of a permanent state of emergency, due to indigenous revolt.