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)

Professional dancer Sandy Lewis, from Louisiana, performs with his dance partner Marti Gasol, as they train in the street due to restrictions to do it indoor, in Barcelona on Wednesday, November 11, 2020 as Spain continue with new measures against the COVID-19. (Photo by Emilio Morenatti/AP Photo)

A woman wearing a mask to help protect against the spread of coronavirus, tries to communicate with Efe, a cat living in Kugulu public garden, in Ankara, Turkey, Monday, November 30, 2020.Turkey's President Recep Tayyip Erdogan has announced Monday the most widespread lockdown so far amid a surge in COVID-19 infections, extending curfews to weeknights and full lockdowns over weekends. (Photo by Burhan Ozbilici/AP Photo)

Goose, a nine-month-old cat, sits in a backpack as people gather during a Speak Out Against Sexual Violence demonstration at Eastern Michigan University in Ypsilanti, Michigan, U.S., March 28, 2021. (Photo by Emily Elconin/Reuters)

A tiger plays in water at a tiger zoo in Chaing Mai, Thailand on March 31, 2021. (Photo by Soe Zeya Tun/Reuters)

Commuters wear protective face masks as they walk through a subway station, in Sao Paulo, Brazil, Wednesday, December 1, 2021, amid the COVID-19 pandemic. Brazil joined the widening circle of countries to report cases of the omicron variant. (Photo by Andre Penner/AP Photo)

A cat wearing a dress is carried around in a transparent rucksack at the annual Pet Expo Thailand 2021 in Bangkok on November 25, 2021. (Photo by Jack Taylor/AFP Photo)

Postal worker Eddie Smith, dressed as Santa Claus, waves to a neighbor on his mail route in Washington, U.S., December 21, 2021. (Photo by Evelyn Hockstein/Reuters)