11 August 1960
The French received considerable resistance in the 1920s to their plan to make Chad a French protectorate – under the command of conqueror Rabih al-Zubayr, the Kimgdoms of the Kanem-Bournu, Baguirmi and Ouaddai fought consistently for the region. When the two armies met at Fort-Foureau (Kousseri) along the Logone River, the Islamic ruler and his kingdoms were all defeated and a French territory was established in 1946 as part of French Equatorial Africa. The fight for independence did not end and due to consistent civil unrest, as well as the changes that needed to be made to the French empire in response to the military, economic and population losses suffered in WWII, the French attempted various stages of divestment and disengagement from the region. Chad was given sectional autonomy in the French community in 1957 however the indigenous population continued resistance efforts and by 28 November 1958 the French National Assembly decided to make Chad a self-governing territory with an aim towards a transition into full independence. Full and autonomous independence was declared for Chad by 11 August 1960 with Francois N'Garta Tombalbaye being elected as president of the newly-independent African state.
References

Gascoigne, B. (2016). History of Chad. Retrieved from History World: https://www.historyworld.net/wrldhis/PlainTextHistories.asp?historyid=ad40|Jones, D. H. (2016). Chad. Retrieved from Encyclopedia Britannica: https://global.britannica.com/place/Chad/Independence