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)

Two three-month-old female white Bengal tiger cubs play with a zoo keeper in their enclosure at the Buenos Aires' Zoo, in Argentina, on April 17, 2014. Captive white Bengal tiger Cloe, gave birth to three cubs – two females and one male – on January 14, 2014. (Photo by Juan Mabromata/AFP Photo)

In this photograph taken on April 16, 2014, a veterinary staff member of the Sumatran Orangutan Conservation Programme center conducts medical examinations on a 14-year-old male orangutan found with air gun metal pellets embedded in his body in Sibolangit district in northern Sumatra island. (Photo by Sutanta Aditya/AFP Photo)

Cardi B attends the Fanatics Super Bowl Party at College Football Hall of Fame on February 2, 2019 in Atlanta, Georgia. (Photo by Shareif Ziyadat/WireImage)

Katie Loynes of the Blues attempts to mark the ball during the AFLW Preliminary Final match between the Carlton Blues and the Fremantle Dockers at Ikon Park on March 23, 2019 in Melbourne, Australia. (Photo by Mike Owen/Getty Images)

Emily Ratajkowski and Vanessa Hudgens attend the 73rd Annual Tony Awards at Radio City Music Hall on June 09, 2019 in New York City. (Photo by Mike Coppola/Getty Images for Tony Awards Productions)

Supporters react as U.S. President Donald Trump walks from Marine One to the White House in Washington, U.S., October 3, 2019. (Photo by Tom Brenner/Reuters)

This photo taken on November 4, 2019 shows people taking part in a fish catching competition in a paddy field in Leishan county in China's southwestern Guizhou province, to celebrate the new year festival Miao people. (Photo by AFP Photo/China Stringer Network)