First, the 8,000 men of Iraq's 51st Infantry Division were reported to have surrendered to American-led invading forces. Then defense officials said they really had just fled.

But in another twist Tuesday, they appeared to have risen again -- to do battle with British troops in the southern city of Basra.

The Pentagon said the confusion was probably more work of the Fedayeen Saddam -- Saddam Hussein's most trusted paramilitary accused of organizing such battlefield ruses as posing as civilians and faking surrenders.

"I think we think the 51st has surrendered," Air Force Gen. Richard Myers, chairman of the Joints Chiefs of Staff, said Tuesday.

Defense Department officials reported Friday, just hours after the start of the ground invasion, that they won the surrender of the entire 51st Division (Mechanized), a regular Iraqi army unit deployed in southern Iraq to defend Basra, the nation's second largest city.

The division was reported to have about 200 tanks.

On Saturday, officials backtracked, saying they had only taken a couple of commanders and the rest of the men had "melted away" -- a term used for those who laid down their arms and returned home.

On Monday there were reports that one of the "commanders" turned out to be a junior official who misrepresented his rank in hopes of getting better treatment.

Then on Tuesday, British forces reported a tank battle with elements of the 51st outside of Basra. Asked about the confusion at a Pentagon press conference, Myers said he believed the division's equipment was taken over by the Fedayeen and possibly members of Saddam's Republican Guard, his best-trained troops.

"Some of their equipment may have been used by the Fedayeen perhaps, or other folks that Fedayeen brought with them," he said. "I mean, supposedly there were some, maybe perhaps a Republican Guard members who changed to civilian clothes and came south. But I have seen no reliable evidence yet -- and it may be because we haven't seen it yet -- that the 51st is reconstituted."

Myers said most of the division ran away but left their equipment in place.

"They did have a tank battle today with some of their equipment," he said of British troops, adding "they were defeated by the British."

Fedayeen Saddam -- whose name means "those ready to sacrifice themselves for Saddam" -- have been putting up stiff resistance and trying to prevent regular army soldiers from surrendering.

Reports from the front suggest Fedayeen members dispatched from Baghdad to outlying areas in recent weeks may have organized battlefield ruses, then turned on invading troops. Such scenes played out in An Nasiriyah and Umm Qasr, where the advancing troops suffered their first major casualties.

"The regime has committed acts of treachery on the battlefield, dressing their forces as liberated civilians and sending soldiers out waiving white flags ... with the goal of drawing coalition forces into the ambushes, using Red Cross vehicles to courier military instructions," Defense Secretary Donald H. Rumsfeld said in Tuesday's news conference with Myers.

He said they are a violation of the rules of war and the acts of a desperate regime.