BENGHAZI, Libya — The field marshal stares from billboards into the wreckage of the Libyan city of Benghazi. His uniform is festooned with epaulets and honors, even as the civil war he is waging has stalled into a bloody stalemate.

His plainclothes security agents loiter and listen in cafes and hotel lobbies. He has handed control of the mosques to extremist preachers. And he has showered patronage on a tribal death squad called the Avengers of Blood, blamed for a long string of disappearances and killings of his political opponents.

“We are living in a prison,” said Ahmed Sharkasi, a liberal activist from Benghazi who fled to Tunis because of threats on his life.

Khalifa Hifter, the 76-year-old commander known in his dominion as “the marshal,” is the military ruler of eastern Libya. He has been fighting for nearly six years to take control of the country, and he has been waging an assault on the capital, Tripoli, for the last 10 months.