The Ride of the Valkyries (Ritt der Walküren) is the popular name for the beginning of the third act of The Valkyrie, the second opera of Richard Wagner's The Ring of the Nibelung cycle. As a separate piece, the Ride is often heard in a purely instrumental form, lasting around three minutes, and it is one of Wagner's best known pieces. In the opera itself, the piece takes eight minutes to be performed, and it sets the scene where the Valkyries are preparing to transport the fallen heroes to Valhalla. After the first performance of the opera in 1870, Wagner started receiving request for the Ride to be performed separately, which he denied, considering a separate performance 'an utter indiscretion'. Some years later he gave in to the requests. The Ride of the Valkyries remains a popular concert encore, especially when other Wagnerian extracts feature in the scheduled program. In popular culture, it is often associated with the film Apocalypse Now, where the 1/9 Air Cavalry regiment plays the piece of music on helicopter-mounted loudspeakers during their assault on a Vietnamese village as psychological warfare and also to motivate their own troops.