The Oak Ridge Boys (also known as simply the Oaks) are an American country and gospel vocal quartet. The group was founded in the 1940s as the Oak Ridge Quartet. They became popular in southern gospel during the 1950s. Their name was officially changed to the Oak Ridge Boys in the early 1960s, and they remained a gospel group until the mid-1970s, when they changed their image and concentrated on country music.

In 1962, Ron Page left, and the group hired Gary McSpadden (who had filled in for Jake Hess in the Statesmen Quartet) as baritone with the understanding from Jake Hess that when he was ready to start a group, he would recruit McSpadden. They recorded another album on Skylite, and then two groundbreaking albums on Warner Brothers. When Hess followed through on that promise, McSpadden quit to join a new group Hess was forming, the Imperials. Jim Hammill (who later became a mainstay in the Kingsmen Quartet) was chosen to be his replacement. They made one album for Festival Records, one for Stateswood (Skylite's budget label), and two more for Skylite. Hammill did not get along with the rest of the group, and William Lee Golden, a newcomer to the music industry, felt that Hamill was hurting the group and asked the group if he could be Hammil's replacement. After Hamill's retirement from the group in 1964, Golden joined as baritone.  The group recorded another album for Starday and another on Skylite in 1965. In 1966, Gatlin left the group to become a minister of music and, on Golden's recommendation, Duane Allen, formerly of the Southernairs Quartet (and more recently baritone of the Prophets Quartet), was hired to replace him. With Willie Wynn still singing tenor and Herman Harper as bass, the group made another album for Skylite, one for United Artists, and then began recording on the Heart Warming label. Between 1966 and 1973 they made 12 albums with Heart Warming, and the company also released several compilation albums on which they were included during those years. The group also had an album on Vista (Heart Warming's budget label) that included unreleased songs from previous sessions. Harper left the group in 1968 to join the Don Light Talent Agency, before starting his own company, The Harper Agency, which remains one of the most highly-reputable booking agencies in gospel music. Noel Fox, formerly of the Tennesseans and the Harvesters, took over the bass part. In 1970, the Oak Ridge Boys earned their first Grammy award for "Talk About the Good Times".  In late October 1972, Richard Sterban, the bass with J.D. Sumner and the Stamps Quartet left that group and joined the Oak Ridge Boys. This closely followed what was possibly the Stamps Quartet's most famous moment, backing Elvis Presley in his 10 June 1972 concert at Madison Square Garden. The quartet that appeared on "Hee Haw" in 1972 consisted of Willie Wynn, Duane Allen, William Lee Golden, and Richard Sterban. Joe Bonsall, a Philadelphia native who was a member of the Keystone Quartet and recording on Duane Allen's Superior label, joined in October 1973 (coincidentally, both Sterban and Bonsall had been members of the Keystones during the late '60s, recording much of the ORB's material). That same year the Oak Ridge Boys recorded a single with Johnny Cash and the Carter Family, "Praise the Lord and Pass the Soup", that put them on the country charts for the first time. The group's lineup would remain consistent for the next 15 years.

Using a quote from the above article, answer the following question: What was his group called?
the Imperials.