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)

This photo taken on April 5, 2013 shows Buddhist monks passing a yak in Seda Monastery, the largest Tibetan Buddhist school in the world, with up to 40,000 monks and nuns in residence for some parts of the year. Seda, known to Tibetans as Serthar is located in Ganzi prefecture in the west of China's Sichuan province and has become a hotbed of protests and violence since the Tibetan uprisings of March 2008. (Photo by Peter Parks/AFP Photo)

Russian opposition leader, Alexei Navalny (C), reacts as the court delivers the verdict in his trial, in the city of Kirov, Russia, 18 July 2013. Alexei Navalny was sentenced to five years in jail for theft on Thursday, an unexpectedly tough punishment which supporters said proved President Vladimir Putin was a dictator ruling by repression. (Photo by Valentina Svistunova/EPA)

Three very colouful alpacas enjoy the hot weather at Toft Farm, Rugby, on July 19, 2013. (Photo by Caters News)

Gorillas at Royal Burgers’ Zoo, Arnhem, Netherlands, on November 28, 2013. (Photo by Vidi Photo/Startraks Photo New York)

Jack, a Lurcher from Dogs Trust Salisbury, walks past a window display of models in a Dogs Trust shop window in Salisbury, as part of a campaign to discourage the impulse buying of dogs ahead of Valentine's Day, on February 10, 2014. (Photo by Matt Alexander/PA Wire)

“MSC Fabiola is a container ship owned by Mediterranean Shipping Company (MSC), the largest such vessel ever to dock in North America. In March 2012 the ship shifted from its initial Asia-to-Europe service to begin trans-Pacific service. On March 19, 2012, Fabiola docked at the Port of Long Beach, breaking earlier records for the largest container ship at a US port, and at any North American port”. – Wikipedia

Photo: The container ship MSC Fabiola (R) is seen docked at the Port of Oakland on March 22, 2012, in Oakland, California. The MSC Fabiola is the largest container ship ever to dock at any seaport in North America with an overall length of nearly one quarter mile long. (Photo by Justin Sullivan/Getty Images)

The Genghis Khan Statue is a 40-metre tall statue of Ghengis Khan (1162–1227) on horseback, on the bank of the Tuul River at Tsonjin Boldog (54 km east of the capital Ulan Bator), where according to legend, he found a golden whip.