More than three years have passed since the French military intervened in Mali to root out radical Islamists who had seized the northern half of the country. Operation Serval, which began in January 2013 as militants marched on the central Malian city of Mopti, marked a turning point in French President Francois Hollande's administration -- in no small part by thawing the leader's chilly relationship with his Chadian counterpart, Idriss Deby. But the operation also underscored Chad's enduring importance to France, regardless of the figures leading the two countries. For more than a century, the African nation has served as a garrison protecting Paris' sway in the region -- influence that France will be loath to give up. Given the advantages a friendship with France can offer Chad as well, little is likely to shake the tight bonds connecting the two in the years ahead....