People in Mexico wave at U.S. Border Patrol agents on horseback patrolling the U.S.-Mexico border fence near San Diego, California, U.S., November 10, 2016. (Photo by Mike Blake/Reuters)

A Cuban migrant couple rests inside a tent at a provisional shelter in Paso Conoa, at the border with Costa Rica March 20, 2016. More than 1,500 Cuban immigrants are waiting at Costa Rica's southern border with Panama as they seek overland passage towards the United States, according to local officials. (Photo by Carlos Jasso/Reuters)

Young girls carry containers filled with drinking water beside the railway station in Agartala, India, April 20, 2016. (Photo by Jayanta Dey/Reuters)

Vendors selling marigold garlands, which are used to decorate temples and homes during the Hindu festival of Durga Puja, drink tea as they wait for customers at a wholesale flower market in Kolkata, India October 6, 2016. (Photo by Rupak De Chowdhuri/Reuters)

Tea garden workers carry sacks of tea leaves at Fatikchera tea garden estate on the outskirts of Agartala, India, May 10, 2016. (Photo by Jayanta Dey/Reuters)

In this November 21, 2015 photo, Camila Lopez Rivas, 14, poses for portraits on a beach in Havana, Cuba, as an assistant lifts the train of her dress to make it look like its flying in the wind. Camila lives in Miami, the daughter of a truck driver who left Cuba when she was a baby. She doesn't remember the island, but wanted to return for the photographs and videos that Latin American girls typically take for their 15th birthdays. (Photo by Ramon Espinosa/AP Photo)

An infrared portrait from NASA's Spitzer Space Telescope which shows generations of stars is seen in this undated NASA handout image released February 14, 2013. In this wispy star-forming region, called W5, the oldest stars can be seen as blue dots in the centers of the two hollow cavities (other blue dots are background and foreground stars not associated with the region). Red shows heated dust that pervades the region's cavities, while green highlights dense clouds. (Photo by NASA/Reuters/JPL-Caltech/Harvard-Smithsonian/Handout)

In the spring of 1965, within weeks of 3,500 American Marines arriving in Vietnam, a 39-year-old Briton named Larry Burrows began work on a feature for LIFE magazine, chronicling the day-to-day experience of U.S. troops on the ground – and in the air – in the midst of the rapidly widening war. The photographs in this gallery focus on a calamitous March 31, 1965, helicopter mission; Burrows’ “report from Da Nang”, featuring his pictures and his personal account of the harrowing operation, was published two weeks later as a now-famous cover story in the April 16, 1965, issue of LIFE.

Photo: Man your battle stations: The crew chief of helicopter Yankee Papa 13, lance corporal James C. Farley, mans an M-60 machine gun during a mission near Da Nang, Vietnam on March 31, 1965. (Photo by Larry Burrows/Time & Life Pictures)