Army Private Bradley Manning is escorted away from his Article 32 hearing February 23, 2012 in Fort Meade, Maryland. (Photo by Mark Wilson/Getty Images)

Supporters of Bradley Manning, the Army private who admitted to leaking classified information to Wikileaks, will hold a rally outside Fort Meade, Md. tomorrow Saturday, two days before his trial by court-martial will begin.

Attendees, who oppose Manning’s imprisonment, will march to the military base at 2 p.m. and will gather to hear speakers an hour later. Speakers scheduled to appear include Daniel Ellsberg, the military analyst who leaked the Pentagon Papers to The New York Times; Ethan McCord, a soldier who saved the children seen in the “Collateral Murder” video released by WikiLeaks; Retired Col. Ann Wright, the most senior State Department official to resign in protest of the Iraq war; Birgitta Jonsdottir, a member of the Icelandic parliament; Sarah Shourd, a hiker who was detained by the Iranian government for nearly two years; and Dan Choi, a former Army lieutenant and prominent opponent of the former “Don’t Ask, Don’t Tell” policy.

Just under 1,500 people have registered to attend the event on Facebook. Transportation from cities including Washington, New York City and Minneapolis is available.

Manning pleaded guilty in March to 10 of the 22 charges against him, including misusing classified material that “disturbed” him. This included a video of an airstrike in Baghdad that killed a Reuters photographer and injured two children. But the 25-year-old said he did not aide the enemy, which is the most serious charge against him. Manning could face up to 20 years in prison for the charges he’s pleaded guilty to and could face life imprisonment if he’s found guilty of aiding the enemy.

Officials from Fort Meade told the Baltimore Sun they will close the main gate of the base Saturday.