One very small example: at least 30 former Guantanamo Bay detainees have been killed or recaptured after taking up arms against allied forces following their release. And these 30 are just those recaptured or those who intelligence sources have identified as having returned to their terror activities upon release, so the number could be even higher.
An analysis of 516 Guantanamo detainees found 95 per cent were a potential threat to US interests. This was based on their affiliations with groups such as al-Qaeda, their enthusiasm for violent jihad, their having undertaken small-arms training or having been willing to perform a support role for terrorism.
That's just one very small, older example. There are many more.
http://www.renewamerica.us/columns/huston/070817
Also, Qari Esmhatulla, an Afghan Pushtun, was captured during Operation Anaconda, the U.S. military offensive in the mountains of eastern Afghanistan in March 2002. He admitted he had carried grenades to Taliban fighters during the mountain battle.
Yemeni national Salim Ahmed Hamdan admits to having been binLaden's personal driver and bodyguard. He was captured by U.S. forces in Afghanistan more than four years ago and is being held at Club Gitmo.
U.S. forces in Iraq capture terrorist Abu Abbas:
http://findarticles.com/p/articles/mi_m0WDQ/is_2003_April_21/ai_100443218
Iraqi, U.S. Troops Capture Terrorists, Weapons Caches:
http://www.defenselink.mil/news/newsarticle.aspx?id=18419
US Raids Capture AQI Terrorists, Iranian Weapons:
http://www.captainsquartersblog.com/mt/archives/009815.php
Iraqi Police capture suspected terrorists :
http://www.blackanthem.com/News/iraqi-freedom/Iraqi-Police-capture-suspected-terrorists14256.shtml
U.S. Soldiers Capture Terrorists, Thwart Terrorist Acts in Iraq:
http://www.globalsecurity.org/military/library/news/2005/09/mil-050924-afps01.htm