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 monarch butterfly rests on the ground at the Sierra Chincua butterfly sanctuary on a mountain in Angangeo, Michoacan November 24, 2016. Angangueo is a town and municipality located in far eastern Michoacán state in central Mexico noted for its history of mining and its location in the Monarch Butterfly Biosphere Reserve. The Monarch Butterfly Biosphere Reserve is a World Heritage Site containing most of the over-wintering sites of the eastern population of the monarch butterfly. (Photo by Carlos Jasso/Reuters)

A chimpanzee looks in the direction of a camera at the Gut Aiderbichl Sanctuary for Traumatized Chimpanzees and other Primates in Gaenserndorf, near Vienna, 17 September 2018. 34 former laboratory chimpanzees of former Austrian pharmaceutical company Immuno AG spend their lives at the Gut Aiderbichl Sanctuary for Traumatized Chimpanzees and other Primates since 2009. (Photo by Christian Bruna/EPA/EFE)

Marani Devi Chaudhary (C), aged 40, performs a ritual in front of shaman Paltan Yadav (unseen) at her home in Rajaur village in Dhanusha district, Nepal, 02 November 2017. The shaman identified Marani Devi to be possessed by their lineage god who was dissatisfied by their worship is thought by the family to have caused them misfortune and is even feared lead to their death. (Photo by Narendra Shrestha/EPA/EFE)

An Indian Royal Bengal tiger looks on at an enclosure on World Tiger Day at Alipore Zoo, Kolkata, India, 29 July 2019. Kolkata zoo authority added a new Tiger to the zoo for the visitors to mark the Tiger Day. Students of Kolkata are also taking part in an awareness campaign aiming to draw attention to the threats that tigers face due to habitat loss and poaching. (Photo by Piyal Adhikary/EPA/EFE)

A wild golden jackals (Canis aureus) mother and her cub entered a house for food at noon. The baby was curiously sniffing all things beside him trying to enter the room of the house and her mother immediately roared and warned her. This photo was taken ahead of the International Day for Biological Diversity 2022 at Tehatta, West Bengal, India on May 21, 2022. (Photo by Soumyabrata Roy/NurPhoto via Getty Images)

Rajasthani Artist During Closing ceremony of annual Camel Fair in Pushkar, India on November 8, 2022. (Photo by Stringer/Anadolu Agency via Getty Images)

Afghan wrestlers compete in a bout of traditional mud wrestling competition during the Friday weekend at a field in Chaman-e- Huzuri ground in Kabul on October 21, 2022. (Photo by Wakil Kohsar/AFP Photo)