Pakistani female police commandos attend a training session in Nowshera, near Peshawar Pakistan, Wednesday, February 11, 2015. Authorities formed a Special Combat Unit after Taliban militants stormed a Peshawar school on Dec. 16, 2014 and massacred 150 children and teachers. (Photo by Mohammad Sajjad/AP Photo)

Alessandra Perilli, of San Marino, competes during the trap women's qualification at the 2016 Summer Olympics in Rio de Janeiro, Brazil, Sunday, August 7, 2016. (Photo by Hassan Ammar/AP Photo)

Crowds watch surfers as the first big swell of the year arrives in Nazaré, Portugal on October 28, 2015. (Photo by Pedro Miranda/Demotix/Corbis)

Military school cadets take part in a ceremony commemorating the 56th anniversary of the death of Camilo Cienfuegos who, along with Fidel Castro and Che Guevara, was a chief commander of the Cuban revolution in Havana, Cuba on October 28, 2015. (Photo by Xinhua/REX Shutterstock)

Tong Jieping, 44-year-old mentally disabled patient, is chained by his foot inside his room, in Qunxing village of Wangjiang county, Anhui province, China, July 14, 2015. Tong was diagnosed mentally ill when he was in his 20s. His parents, both in their 70s, could not afford the medical treatments so they had to lock him up in chains to prevent him from running away, according to Tong's family. (Photo by Reuters/Stringer)

Baloo (R), a North American Black Bear, rubs snouts with his companion Shere Hkhan, a Bengal tiger, inside their shared enclosure at Noah's Ark animal sanctuary in Locust Grove, Georgia, USA, 28 August 2014. According to the facility, the pair and a lion named Leo, were confiscated at a young age from a drug dealer's basement in Atlanta, Georgia. Noah's Ark cares for about 100 different species of animals on a 250 acre farm since 1990. (Photo by Erik S. Lesser/EPA)

British Waters Wide Angle category runner-up. Grass snake swimming along a garden pond by Jack Perks (UK)in Nottinghamshire, UK. “I’m always on the lookout for unusual freshwater subjects and grass snakes are a species I’ve been after for years. I was told about a pond where the odd grass snake hangs around the lilly pads for frogs. I put my drysuit on and got into the water and could see one slithering along the surface. Slowly making my way towards it with my head only just poking above I got the spilt shot”. (Photo by Jack Perks/Underwater Photographer of the Year 2019)

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)