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)

Characters dressed as Elmo and Cookie Monster who pose for tips take a photo by request from a tourist (2nd R, black pants) in Times Square in the Manhattan borough of New York City, January 29, 2016. (Photo by Rickey Rogers/Reuters)

A man dresses as a Minion tries to convince a tourist to have her picture taken with him, in Times Square, in New York, April 7, 2016. The assortment of costumed characters, painted naked women and ticket sellers who make the streets of New York's Times Square their office, catering to tourists, may soon be restricted after a City Council vote Thursday. (Photo by Rickey Rogers/Reuters)

A male deer barks at dawn during the annual deer rutting season at Richmond Park in London, Britain, October 9, 2016. (Photo by Toby Melville/Reuters)

Figurative lanterns for Lunar New Year hang over a road to mark the upcoming Year of the Ox in Singapore on January 19, 2021. (Photo by Roslan Rahman/AFP Photo)

In this January 16, 2019 photo, a sculpture of a Plesiosaur is displayed at an exhibit about the studies of researchers from the National Museum made in Antartica, during a media presentation of the exhibit in Rio de Janeiro, Brazil. The National Museum will inaugurate on Jan. 17 their first exhibition after the fire, held at the building that houses the Cultural Center and Museum of Brazil's Mint. (Photo by Leo Correa/AP Photo)

Ryon Healy #25 of the Oakland Athletics is covered in water by Adam Rosales #16 after he hit a walk-off home run in the ninth inning against the Detroit Tigers at Oakland Alameda Coliseum on May 7, 2017 in Oakland, California. (Photo by Ezra Shaw/Getty Images)

Sally Rand dances on a beach in St. Petersburg, Florida, February 17, 1936. (Photo by AP Photo)