Boko Haram's terror has spread beyond Nigeria's borders. In mid-June the recently declared Islamic State-affiliate staged two suicide attacks in the Chadian capital N'djamena, killing 23 people. The expanding threat posed by the militant group was answered earlier this year by a regional coalition of forces from Chad, Niger, and Cameroon who agreed to assist Nigeria's own beleaguered army.

Chad's contingent of 5,000 soldiers has advanced the furthest into Nigeria. One of the most experienced fighting forces in the region, Chad says they've killed hundreds of Boko Haram militants while losing few of their own troops.

Meanwhile, thousands of refugees and displaced people have sought shelter in Chad's Lake Region, which houses some of most destitute communities in one of the poorest countries in the world.

In this excerpt from 'Chad's Fight Against Boko Haram,' VICE News is shown graphic cellphone footage of beheadings carried out by Boko Haram, seized by the Chadian army during operations in Nigeria.

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