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 three-month-old Sumatran tiger cub named “Bandar” shows his displeasure after being dunked in the tiger exhibit moat for a swim reliability test at the National Zoo in Washington, on November 6, 2013. All cubs born at the zoo must take a swim test before being allowed to roam in the exhibit. Bandar passed his test. (Photo by Manuel Balce Ceneta/Associated Press)

Karis, an eleven week old lion cub, plays in fallen leaves brushed up by keepers in her enclosure at Blair Drummond Safari Park, near Stirling, Scotland, on November 20, 2013. (Photo by Andrew Milligan/PA Wire)

Sarah Paulson and Amanda Peet arrive at the 20th annual Screen Actors Guild Awards. (Photo by Jordan Strauss/AP Photo/Invision)

Fire retardant is dropped on the Fairview Fire burning near Hemet, California, U.S., September 6, 2022. (Photo by David Swanson/Reuters)

Colorado Rockies' Charlie Blackmon, back, douses Randal Grichuk as he is interviewed by field announcer Kelsey Wingert, right, following Grichuk's three-run home run off Milwaukee Brewers relief pitcher Taylor Rogers during the 10th inning of a baseball game Tuesday, September 6, 2022, in Denver. (Photo by David Zalubowski/AP Photo)

Artists perform during a “Yandu Story” Show performance, in Yancheng, Jiangsu province, China, 20 September 2022. The story dates back to some 100 years when – according to the organizers – two prominent local families, Gu and Ling, were committed to get out of a predicament, but parted due to different development concepts and ended in a turmoil. The large-scale immersive series of performances took more than a year of careful planning and consists of two parts: a daytime performance and a 90-minute night performance, they added. (Photo by Alex Plavevski/EPA/EFE/Rex Features/Shutterstock)