A Puffing Billy steam train hauled by locomotive 14A crosses the Monbulk Creek trestle after leaving Belgrave station near Melbourne, October 20, 2014. While the discovery of steam power 200 years ago powered the Industrial Revolution, the world long ago shunted most steam trains onto the sidings of history. (Photo by Jason Reed/Reuters)

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)

Among the fish populations that could be harmed by the Xayaburi dam in Laos is the critically endangered Mekong giant catfish, considered by the Guinness Book of World Records to be the world’s largest freshwater fish. The fish, which grows to 650 pounds and about 10 feet long, is only found in the Mekong River. It is migratory, moving between downstream habitats in Cambodia upstream to northern Thailand and Laos each year to spawn. Some experts fear the Xayaburi dam could block the migration and drive the giant catfish to extinction. (Photo by Courtesy of Zeb Hogan/University of Nevada, Reno)

Four-year-old Solaris Arias (right) jumps through water spraying from an open fire hydrant in Providence, Rhode Island, on June 20, 2012. Much of the state remained under a heat advisory Tuesday afternoon because of the steamy air mass that has moved into the region resulting in temperatures in the 90s. (Photo by Steven Senne/AP Photo)

The Flying Bull's P-38 Lockheed Lightning N25Y / 13 – Red Bull – Flying Legends Airshow 2012 Duxford (Photo by Rob Lovesey)

“The Lun-class ekranoplan (NATO reporting name Duck) was a ground effect vehicle (GEV) designed by Rostislav Evgenievich Alexeev and used by the Soviet and Russian navies from 1987 until sometime in the late 1990s. It “flew” using the lift generated by the ground effect of its large wings when close to the surface of the water – about four metres or less. Although they might look similar and/or have related technical characteristics, ekranoplans like the Lun are not aircraft, seaplanes, hovercraft, or hydrofoils – ground effect is a separate technology altogether. The International Maritime Organization classifies these vehicles as maritime ships. The name Lun comes from the Russian for harrier”. – Wikipedia (Photo by Igor113)

A fan dressed as “Loki” poses before the European premiere of “Avengers: Age of Ultron” at Westfield shopping centre in Shepherds Bush, London April 21, 2015. (Photo by Stefan Wermuth/Reuters)

Eleven-year-old Kelen loves to dance in the half-built rooms of the centre in Kabanga Refuge Centre, Tanzania, 2012. The rescue centres protect albino people from the vicious hunters who sell their body parts to witch doctors. Photojournalist Ana Palacios, 43, visited the centre in Tanzania three times between 2012 and 2016 to find out more about the plight of albino people. (Photo by Ana Palacios/Barcroft Images)