Nightwish is a symphonic metal band from Kitee, Finland. The band was formed in 1996 by lead songwriter and keyboardist Tuomas Holopainen, guitarist Emppu Vuorinen, and former lead singer Tarja Turunen. The band soon picked up drummer Jukka Nevalainen, and then bassist Sami Vanska after the release of their debut album, Angels Fall First (1997). In 2001, Vanska was replaced by Marco Hietala, who also took over the male vocalist role previously filled by Holopainen or guest singers.

On October 7, 1998, Nightwish released their second full-length album, Oceanborn, in Finland only. Adopting a more technical and progressive sound than Angels Fall First, Oceanborn saw the band abandon much of the ambient and folk elements present on their debut release, with the exception of the song "Moondance". In contrast to the female vocals of Turunen, the album also featured guest growling vocals by Tapio Wilska (ex-Finntroll), since Tuomas did not want to sing again. Wilska is also a former member of Nattvindens Grat.  AllMusic review said that the album "as a whole works great", with songs that are "very strong". Oceanborn was an instant success in Finland, reaching number 5 on the Finnish album charts. The album's first single, "Sacrament of Wilderness", hit number 1 on the Finnish singles charts, where it stayed for several weeks. The album's release was initially limited to Finland, but because of the success of "Sacrament of Wilderness", Spinefarm released Oceanborn internationally in the spring of 1999. In May 1999, Nightwish recorded the single "Sleeping Sun (Four Ballads of the Eclipse)", and in one month the single sold 15,000 copies in Germany alone. Following the band's first international success, Nightwish was added as the opening band for Rage's 1999 European tour. Both the album Oceanborn and the singles "Sacrament of Wilderness" and "Walking in the Air" were certified gold in Finland in August 1999.  While in the studio in early 2000 working on their third album, Nightwish was accepted in the Finnish Eurovision Song Contest tryouts with the song "Sleepwalker". Despite winning the public vote, Nightwish eventually finished in second place, with the jury choosing local gospel singer Nina Astrom to represent Finland.  On May 19, 2000, Nightwish released their third studio album Wishmaster. This debuted at No. 1 on the Finnish album charts, and was certified gold in Finland after three weeks at number one. Critical response to the album was mixed, with Allmusic citing the album as repetitive, and saying "as a whole album, it can be a little annoying, even frustrating". However, German magazine Rock Hard declared Wishmaster "Album of the Month", despite competing against long-awaited May releases from Iron Maiden and Bon Jovi. Following the release of Wishmaster, Nightwish embarked on their first world tour, playing dates in South America, Mexico, Canada, and the first headlining European tour with Sinergy and Eternal Tears of Sorrow. In the summer, the band returned to Europe, appearing at the Wacken Open Air festival and the Biebop Metal Fest.

Answer the following question by taking a quote from the article: What singles were released?
The album's first single, "Sacrament of Wilderness