A reveller takes part in an annual block party known as “Cordao de Prata Preta”, one of the many carnival parties to take place in the neighbourhoods of Rio de Janeiro, February 6, 2016. (Photo by Pilar Olivares/Reuters)

A man falls from an ox cart as he competes during an ox cart competition near U Bein bridge, in Mandalay March 22, 2015. (Photo by Soe Zeya Tun/Reuters)

A relative (L) of Champa Devi, 88, sits next to her body, minutes after her death at Mukti Bhavan (Salvation House) at Varanasi, in the northern Indian state of Uttar Pradesh, June 21, 2014. The city of Varanasi, on the banks of the River Ganges, is widely considered Hinduism's holiest city and many Hindus believe that dying there and having their remains scattered in the Ganges allows their soul to escape a cycle of death and rebirth, attaining “moksha” or salvation. “Mukti Bhavan” or “Salvation House”, is a charity-run hostel that caters for people who wish to come to Varanasi to die. Guests can normally stay up to two weeks after which, if they haven't yet passed away, they are gently asked to leave. (Photo by Danish Siddiqui/Reuters)

A wax figure of U.S. actress Scarlett Johansson stands outside Madame Tussauds New York attraction shortly after the figure was unveiled in Times Square in New York, July 30, 2015. (Photo by Mike Segar/Reuters)

A performer wearing costumes walk on stilts before a show during a lantern fair at the beginning of Chinese Lunar New Year, in Xi'an, Shaanxi province, February 11, 2016. (Photo by Reuters/Stringer)

Caoimhe Cooburn-Gray poses for a picture on St. Patrick's day in Dublin, Ireland March 17, 2016. Saint Patrick's Day is a cultural and religious celebration held on 17 March, the traditional death date of Saint Patrick (c. AD 385–461), the foremost patron saint of Ireland. Celebrations generally involve public parades and festivals, céilithe, and the wearing of shamrocks, as well as green or orange attire. (Photo by Clodagh Kilcoyne/Reuters)

A Snowboarder participates in a waterslide contest, which consists of gliding over a water pool embedded in snow, during the closing event of the ski resort of Nendaz, southwestern Switzerland, Monday, April 21, 2014. (Photo by Maxime Schmid/AP Photo/Keystone)

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)