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)

A staff member demonstrates how she puts on the helmet of a mock space suit at the C-Space Project Mars simulation base in the Gobi Desert outside Jinchang, Gansu Province, China, April 17, 2019. The facility – comprising several interconnected modules including a greenhouse and a mock decompression chamber – opened its doors to the public. (Photo by Thomas Peter/Reuters)

British Prime Minister Boris Johnson visits the Pavegen stand, a company that converts footsteps into energy, at the Innovation Zone during the UK-Africa Investment Summit in London, Britain on January 20, 2020. (Photo by Leon Neal/Pool via Reuters)

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)

A man celebrates the start of the New Year, backdropped by fireworks exploding in the background over Copacabana Beach in Rio de Janeiro, Brazil, Saturday, January 1, 2022. (Photo by Bruna Prado/AP Photo)