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 chevrotain or mouse deer feeds in its enclosure at Zurich Zoo, Zurich, Switzerland, October 17, 2012. (Photo by Patrick B. Kraemer/AP)

Flower garlands, fruits and a pair of sandals of a woman who died from the coronavirus disease (COVID-19), are placed by her relatives on the spot where she was cremated, as part of a ritual at a crematorium in New Delhi, India, April 30, 2021. (Photo by Adnan Abidi/Reuters)

Fishermen are seen near thousands of fish found dead at Lake Maninjau due to lack of oxygen levels at the bottom of the lake and bad weather that hit the area in Agam, West Sumatra Province, Indonesia on April 29, 2021. (Photo by Muhammad Arif Pribadi/Antara Foto via Reuters)

Hot-air balloons float over the Oka River during the Russian Sky International Balloon Festival in Ryazan Region, Russia on July 26, 2021. (Photo by Alexander Ryumin/TASS)

Marines of the Baltic Fleet forces of the Russian Navy train in the zone of obstacles during military exercises at the Khmelevka firing ground in the Kaliningrad region, Russia on November 24, 2021. (Photo by Vitaly Nevar/Reuters)

A woman walks past servicemen of the self-proclaimed Donetsk People's Republic (DNR), who take part in a rehearsal for the Victory Day parade in Donetsk, Ukraine on May 3, 2018. (Photo by Alexander Ermochenko/Reuters)

In this Thursday, June 14, 2018, file photo, students wear virtual reality goggles during a science class at Pyongyang Teachers' University, a teacher training college, in Pyongyang, North Korea. (Photo by Dita Alangkara/AP Photo)