An Army private charged in the biggest security breach in U.S. history testified Thursday that he felt like a doomed, caged animal after he was arrested in Baghdad for allegedly sending classified information to the secret-spilling website WikiLeaks.

Pfc. Bradley Manning testified on the third day of a pretrial hearing at Fort Meade, outside Baltimore. His lawyers are seeking dismissal of all charges, contending his pretrial confinement in a Quantico, Va., Marine Corps brig was needlessly harsh.

Before he was sent to Quantico in July 2010, Manning spent some time in a cell in a segregation tent at Camp Arifjan, an Army installation in Kuwait.

"I remember thinking I'm going to die. I'm stuck inside this cage," Manning said under questioning by defense attorney David Coombs. "I just thought I was going to die in that cage. And that's how I saw it — an animal cage."

The compact, 24-year-old intelligence analyst looked youthful in his dark blue dress uniform, close-cropped hair and rimless eyeglasses. He was animated, often swiveling in the witness chair and gesturing with his hands.

Manning is trying to avoid trial in the WikiLeaks case. He argues he was punished enough when he was locked up alone in a small cell for nearly nine months at a brig in Quantico, Va., and had to sleep naked for several nights.

The military contends the treatment was proper, given Manning's classification then as a maximum-security detainee who posed a risk of injury to himself or others.

Earlier Thursday, a military judge accepted the terms under which Manning would plead guilty to eight charges for sending classified documents to the WikiLeaks website.

Col. Denise Lind's ruling doesn't mean the pleas have been formally accepted. That could happen in December.

But Lind approved the language of the offenses to which Manning would admit.

She said those offenses carry a total maximum prison term of 16 years.

Manning made the offer as a way of accepting responsibility for the leak. Government officials have not said whether they would continue prosecuting him for the other 14 counts he faces, including aiding the enemy. That offense carries a maximum penalty of life in prison.

Under the proposal, Manning would admit to willfully sending the following material: a battlefield video file, some classified memos, more than 20 Iraq war logs, more than 20 Afghanistan war logs and other classified materials. He would also plead guilty to wrongfully storing classified information.

Meanwhile, Manning's lawyers are arguing that the charges against the soldier should be dismissed because of how he was treated while confined at Quantico.

Other prospective witnesses include a military psychiatrist who examined Manning at Quantico, and the former commander of the confinement facility at Fort Leavenworth, Kan. Manning was later moved there, re-evaluated and given a medium-security classification.