Chadian troops rescue 85 Nigerian hostages from Boko Haram

From Aminu Abubakar, for CNN

Updated 1535 GMT (2335 HKT) August 17, 2014

A video of Abubakar Shekau, who claims to be the leader of the Nigerian Islamist extremist group Boko Haram, is shown in September 2013. Boko Haram is an <a href="http://www.cnn.com/2014/02/27/world/africa/nigeria-year-of-attacks">Islamist militant group waging a campaign of violence</a> in northern Nigeria. The group's ambitions range from the stricter enforcement of Sharia law to the total destruction of the Nigerian state and its government. Click through to see recent bloody incidents in this strife-torn West African nation:
Photos: Boko Haram: Nigeria's crisis
A video of Abubakar Shekau, who claims to be the leader of the Nigerian Islamist extremist group Boko Haram, is shown in September 2013. Boko Haram is an Islamist militant group waging a campaign of violence in northern Nigeria. The group's ambitions range from the stricter enforcement of Sharia law to the total destruction of the Nigerian state and its government. Click through to see recent bloody incidents in this strife-torn West African nation:
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Photos: Boko Haram: Nigeria's crisis
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Bodies lie in the streets in Maiduguri, Nigeria, after religious clashes on July 31, 2009. Boko Haram exploded onto the national scene in 2009 when <a href="http://www.cnn.com/2012/01/02/world/africa/boko-haram-nigeria/index.html">700 people were killed </a>in widespread clashes across the north between the group and the Nigerian military.
Photos: Boko Haram: Nigeria's crisis
Bodies lie in the streets in Maiduguri, Nigeria, after religious clashes on July 31, 2009. Boko Haram exploded onto the national scene in 2009 when 700 people were killed in widespread clashes across the north between the group and the Nigerian military.
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An official displays burned equipment inside a prison in Bauchi, Nigeria, on September 9, 2010, after the prison was attacked by suspected members of Boko Haram two days earlier. About <a href="http://www.cnn.com/2010/WORLD/africa/09/08/nigeria.prison.break/index.html">720 inmates escaped</a> during the prison break, and police suspect the prison was attacked because it was holding 80 members of the sect.
Photos: Boko Haram: Nigeria's crisis
An official displays burned equipment inside a prison in Bauchi, Nigeria, on September 9, 2010, after the prison was attacked by suspected members of Boko Haram two days earlier. About 720 inmates escaped during the prison break, and police suspect the prison was attacked because it was holding 80 members of the sect.
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Nigerian President Goodluck Jonathan, second from left, stands on the back of a vehicle after being <a href="http://www.cnn.com/2011/WORLD/africa/05/29/nigeria.president.inauguration/index.html">sworn-in as President </a>during a ceremony in the capital of Abuja on May 29, 2011. In December 2011, Jonathan declared a <a href="http://www.cnn.com/2011/12/31/world/africa/nigeria-state-of-emergency/">state of emergency</a> in parts of the country afflicted by violence from Boko Haram.
Photos: Boko Haram: Nigeria's crisis
Nigerian President Goodluck Jonathan, second from left, stands on the back of a vehicle after being sworn-in as President during a ceremony in the capital of Abuja on May 29, 2011. In December 2011, Jonathan declared a state of emergency in parts of the country afflicted by violence from Boko Haram.
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Rescue workers help a wounded person from a U.N. building in Abuja, Nigeria, on August 26, 2011. The building was rocked by a bomb that killed at least 23 people, leaving others trapped and causing heavy damage. Boko Haram had claimed responsibility for the attack in which a Honda packed with explosives <a href="http://www.cnn.com/2011/WORLD/africa/08/31/nigeria.attack.al.qaeda/index.html">rammed into the U.N. building</a>, shattering windows and setting the place afire.
Photos: Boko Haram: Nigeria's crisis
Rescue workers help a wounded person from a U.N. building in Abuja, Nigeria, on August 26, 2011. The building was rocked by a bomb that killed at least 23 people, leaving others trapped and causing heavy damage. Boko Haram had claimed responsibility for the attack in which a Honda packed with explosives rammed into the U.N. building, shattering windows and setting the place afire.
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A photo taken on November 6, 2011, shows state police headquarters burned by a series of attacks that targeted police stations, mosques and churches in Damaturu, Nigeria, on November 4, 2011. Attackers left scores injured -- <a href="http://www.cnn.com/2011/11/05/world/africa/nigeria-attacks/index.html">probably more than 100</a> -- in a three-hour rampage, and 63 people died.
Photos: Boko Haram: Nigeria's crisis
A photo taken on November 6, 2011, shows state police headquarters burned by a series of attacks that targeted police stations, mosques and churches in Damaturu, Nigeria, on November 4, 2011. Attackers left scores injured -- probably more than 100 -- in a three-hour rampage, and 63 people died.
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Men look at the wreckage of a car after a bomb blast at St. Theresa Catholic Church outside Abuja on December 25, 2011. A string of bombs struck churches in five Nigerian cities,<a href="http://www.cnn.com/2011/12/25/world/africa/nigeria-church-bombing/index.html"> leaving dozens dead and wounded on the Christmas holiday</a>, authorities and witnesses said. Boko Haram's targets included police outposts and churches as well as places associated with "Western influence."
Photos: Boko Haram: Nigeria's crisis
Men look at the wreckage of a car after a bomb blast at St. Theresa Catholic Church outside Abuja on December 25, 2011. A string of bombs struck churches in five Nigerian cities, leaving dozens dead and wounded on the Christmas holiday, authorities and witnesses said. Boko Haram's targets included police outposts and churches as well as places associated with "Western influence."
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A paramedic helps a young man as he leaves a hospital in the northern Nigerian city of Kano on January 21, 2012. A spate of bombings and shootings left more than 200 people dead in Nigeria's second-largest city. Three days later, a joint military task force in Nigeria <a href="http://www.cnn.com/2012/01/24/world/africa/nigeria-attacks/">arrested 158 suspected members</a> of Boko Haram.
Photos: Boko Haram: Nigeria's crisis
A paramedic helps a young man as he leaves a hospital in the northern Nigerian city of Kano on January 21, 2012. A spate of bombings and shootings left more than 200 people dead in Nigeria's second-largest city. Three days later, a joint military task force in Nigeria arrested 158 suspected members of Boko Haram.
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A photo taken on June 18, 2012, shows a car vandalized after three church bombings and retaliatory attacks in northern Nigeria killed at least 50 people and injured more than 130 others, the Nigerian Red Cross Society said.