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)

In this file photo taken on Saturday May 1, 1993, an elderly communist woman clutches her head as police on horseback patrol the streets in Moscow. When Alexander Zemlianichenko started working as an AP photographer in Moscow, the Soviet Union was nearing its demise. (Photo by Alexander Zemlianichenko/AP Photo)

Locals harvest their potatoes as Mount Sinabung spews volcanic ash in Karo, North Sumatra province, Indonesia on August 10, 2020. (Photo by Sastrawan Ginting/Antara Foto via Reuters)

Anissa Barbato from New York looks out over the city from the Edge, the highest outdoor sky deck in the Western Hemisphere on September 2, 2020 as it reopened to the public in New York. Rising 1,131 feet in the air from the heart of Hudson Yards it offers 360-degree views of New York Citys iconic skyline from the 100th floor outdoor viewing. (Photo by Timothy A. Clary/AFP Photo)

A man dressed as Father Christmas learns how to use Zoom on a laptop in the grotto at Bamburgh castle in Northumberland, UK on November 3, 2020, it was due to open on November the 21st but due to the new national lockdown he will now be speaking to the children via Zoom on a computer. (Photo by Owen Humphreys/PA Images via Getty Images)

A Lebanese man dressed with a Santa Claus outfit rides on a standup paddle in Lebanon's northern coastal city of Batroun on December 22, 2020. (Photo by Ibrahim Chalhoub/AFP Photo)

Final-year student Alina Repkina prepares for a livestream of the Last Bell ceremony for school leavers at secondary school No 11 in Rostov-On-Don, Russia on May 30, 2020. It is the first time in Russia that such ceremonies have been held via video link due to the coronavirus lockdown restrictions. (Photo by Valery Matytsin/TASS)