( CNN ) -- Supporters of Pfc . Bradley Manning , accused in the largest leak of classified documents in U.S. history , have adopted the phrase : `` I am Bradley Manning . '' But who is Manning ? A whistle-blower ? Or someone who aided the enemy in the midst of war ? Those and other questions go to trial Monday as Manning 's court-martial is scheduled to begin at Maryland 's Fort Meade . Gallery : Key WikiLeaks figures as trial begins . In February , Manning , 25 , pleaded guilty to 10 of the 22 charges against him and faces up to two decades in jail . He did not plead guilty to the most serious charge -- that of aiding the United States ' enemies , which carries the potential for a life sentence . During the proceeding , Manning spent more than an hour reading a statement that detailed why and how he sent classified material to WikiLeaks , a group that facilitates the anonymous leaking of secret information through its website . Manning said he passed on information that `` upset '' or `` disturbed '' him but did n't give WikiLeaks anything he thought would harm the United States if it were made public . `` I believed if the public was aware of the data , it would start a public debate of the wars , '' he told the court . The U.S. military first detained Manning in May 2010 for leaking U.S. combat video -- including a U.S. helicopter gunship attack posted on WikiLeaks -- and classified State Department cables . Manning was turned in by Adrian Lamo , a former hacker , whom Manning allegedly told about leaking the classified records . In his statement to the court , Manning said he initially contacted The Washington Post and The New York Times to provide information . He said he either was n't taken seriously or got voice mail , so he gave the material to WikiLeaks . WikiLeaks has never confirmed that Manning was the source of its information . On Saturday , Manning 's supporters rallied outside Fort Meade . `` People came from great distances to stand with a true American hero , '' said Jeff Paterson , director of the Bradley Manning Support Network . `` From Bradley 's demeanor in court , it 's clear he takes strength from the outpouring of support . '' Manning was formally charged in February 2012 . On the eve of the court-martial , his lawyer , David Coombs , issued a rare public statement through his website . He thanked those who raised money and awareness over the past three years , bringing `` worldwide attention to this important case . '' 2012 : Prosecutors say Manning did n't report any mistreatment to them . CNN 's Carol Cratty , Larry Shaughnessy and Mark Morgenstein contributed to this report .
Pfc . Bradley is accused in the largest leak of classified documents in Maryland history . In February , he pleaded guilty to 22 of the 22 charges against him . He did not plead guilty to the most serious charge -- that of aiding the United States ' enemies . Manning 's supporters rallied at U.S. 's Fort Meade on February .