He soon fell into a rhythm of photographing in the field for a few days and returning to the comfort of Saigon, where he would drink and swap tales with his fellow Western photographers at the Continental hotel. They often wondered about the photographers on the other side who were receiving much more incoming fire — even napalm — and could not enjoy the comfort of a hotel when their day was done.

He and his colleagues sometimes lifted a glass for their unknown compatriots on the other side.

In March 1973 Mr. Chauvel stood on the banks of the Thach Han River in Quang Tri Province to photograph a rare prisoner exchange between the North and South Vietnamese. He remembers feeling nervous that it might not come off as planned as he saw North Vietnamese troops a few hundred feet away. He assumed there was a photographer with them on the other side.

Chu Chi Thanh remembers that day just as clearly: He was the North Vietnamese photographer on the other side of the river. As his North Vietnamese compatriots were released, they jumped out of the boats, he recalled last week at an exhibit of wartime photographs by North Vietnamese photographers that Mr. Chauvel organized at the Visa Pour L’image festival in Perpignan, France.

“It was very emotional,” Mr. Thanh said. “The first thing they did when they were separated from guards was jump off their boats, throw away their prisoner clothes and run in the river towards their friends.”

Though the photographers were just a few hundred feet apart and were probably specks in each other’s photos, Mr. Thanh’s experiences were so different from Mr. Chauvel’s that they might as well have been a thousand miles apart.

Mr. Thanh remembers talking that day with a South Vietnamese photographer who crossed briefly with the released prisoners.

“I asked him why he photographed war and he said it was a job and while they got paid for it, and they accepted the risk as a journalist, nothing was worth a life,” Mr. Thanh said.

Mr. Thanh, 70, said he and his colleagues were unpaid and all expected to die — more than 300 North Vietnamese photographers lost their lives. But their motivation was different, he said.

“We wanted to show the American crimes of invading my country, and I felt I could be useful doing that,” he said.

Mr. Thanh’s photo from the release is in the exhibit “The Photographers in the North” in Perpignan until Sept. 14. The North Vietnamese photographers in the exhibit worked for the army or for government newspapers and lived alongside soldiers, sometimes in underground tunnels.

Joining Mr. Thanh in Perpignan were Cong Tinh, Mai Nam and Hua Kiem, who also photographed on the northern side of the war. Their photos have rarely been seen before in Europe.

The exhibit was the idea of Mr. Chauvel, who traveled to North Vietnam this year along with Jean Francois Leroy, the director of the Visa Pour L’Image photo festival. Mr. Chauvel has also published a book on the North Vietnamese photographers, “Ceux du Nord,” and is making a documentary. The North Vietnamese photographers’ images are equal to the great American photos from the war. In Perpignan, seasoned conflict photographers in attendance were in awe of their elderly North Vietnamese colleagues and gave them a long standing ovation during the evening projections.

The exhibit and book satisfy Mr. Chauvel’s curiosity about the North Vietnamese photographers who were often nearby — though unseen — during battles he covered.

And it rights a wrong.

“Usually, history is written by people who won the wars, but it was written by the losers in Vietnam,” Mr. Chauvel said. “This is the first time that the North Vietnamese photographers are writing the story. It’s about time.”

By James Estrin - The New York Times - September 10, 2014