A chimpanzee looks in the direction of a camera at the Gut Aiderbichl Sanctuary for Traumatized Chimpanzees and other Primates in Gaenserndorf, near Vienna, 17 September 2018. 34 former laboratory chimpanzees of former Austrian pharmaceutical company Immuno AG spend their lives at the Gut Aiderbichl Sanctuary for Traumatized Chimpanzees and other Primates since 2009. (Photo by Christian Bruna/EPA/EFE)

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)

Jorge, an immigrant from Mexico, dressed as the Sesame Street character Elmo rests in Times Square, New York July 29, 2014. Elmo and Cookie Monster have long delighted young viewers on TV's “Sesame Street”, but the recent antics of New York street performers dressed as the beloved characters have drawn the ire of city officials and now the show's producers. Sesame Workshop, which owns the rights to Big Bird, Ernie and the assorted puppet monsters on the 45-year-old program, said on July 29, 2014 it was drafting plans to stop performers who dress up as the characters from appearing in Times Square, where they pose for photos with tourists and then demand tips. (Photo by Eduardo Munoz/Reuters)

(L-R) Singers Kristal Lyndriette, Ashley Williams, Shyann Roberts, Brienna DeVlugt and Gabby Carreiro of June's Diary attend the 2016 BET Awards at the Microsoft Theater on June 26, 2016 in Los Angeles, California. (Photo by Frederick M. Brown/Getty Images)

Meghan Puhr participates in a virtual realty presentation during an Intel news conference before CES International, Wednesday, January 4, 2017, in Las Vegas. (Photo by John Locher/AP Photo)

A woman wearing a protective mask stands as she waits for the bus at the sidewalk, after Indonesia confirmed its first cases of coronavirus, in Jakarta, Indonesia, March 4, 2020. (Photo by Willy Kurniawan/Reuters)

South Korean residents 89-year-old Jeong Nam-poong and 80-year-old Jang Yoon-hui , wearing protective masks, dance at park after their daytime discotheque “colatec” has been closed amid the coronavirus disease (COVID-19) outbreak in Seoul, South Korea, May 19, 2020. (Photo by Minwoo Park/Reuters)

A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. (Photo by Reuters/NASA/ESA/Hubble)