Blood, Sweat & Tears (also known as "BS&T") is a jazz-rock American music group. They are noted for their combination of brass and rock band instrumentation. The group recorded songs by rock/folk songwriters such as Laura Nyro, James Taylor, the Band and the Rolling Stones as well as Billie Holiday and Erik Satie. They also incorporated music from Thelonious Monk and Sergei Prokofiev into their arrangements.

Al Kooper, Jim Fielder, Fred Lipsius, Randy Brecker, Jerry Weiss, Dick Halligan, Steve Katz and Bobby Colomby formed the original band. The creation of the group was inspired by the "brass-rock" ideas of the Buckinghams and its producer, James William Guercio, as well as the early 1960s Roulette-era Maynard Ferguson Orchestra (according to Kooper's autobiography).  Al Kooper was the group's initial bandleader, having insisted on that position based on his experiences with the Blues Project, his previous band with Steve Katz, which had been organized as an egalitarian collective. Jim Fielder was from Frank Zappa's the Mothers of Invention and had played briefly with Buffalo Springfield. Kooper's fame as a high-profile contributor to various historic sessions of Bob Dylan, Jimi Hendrix and others was a catalyst for the prominent debut of Blood, Sweat & Tears in the musical counterculture of the mid-sixties.  Kooper, Colomby, Katz and Fielder did a few shows as a quartet at the Cafe Au Go Go in New York City in September 1967, opening for Moby Grape. Fred Lipsius then joined the others two months later. A few more shows were played as a quintet, including one at the Fillmore East in New York. Lipsius then recruited the other three, Dick Halligan, Randy Brecker and Jerry Weiss, who were New York jazz horn players Lipsius knew. The final lineup debuted at the Cafe Au Go Go on November 17-19, 1967, then moved over to play The Scene the following week. The band was a hit with the audience, who liked the innovative fusion of jazz with acid rock and psychedelia.  After signing to Columbia Records, the group released Child Is Father to the Man. The album cover was considered quite innovative showing the band members sitting and standing with child-sized versions of themselves. The album slowly picked up in sales despite growing artistic differences among the founding members which resulted in several personnel changes for the second album. Colomby and Katz wanted to move Kooper exclusively to keyboard and composing duties, while hiring a stronger vocalist for the group, causing Kooper's departure in April 1968. He became a record producer for the Columbia label, but not before arranging some songs that would be on the next BS&T album. The group's trumpeters, Randy Brecker and Jerry Weiss, also left and were replaced by Lew Soloff and Chuck Winfield. Brecker joined Horace Silver's band with his brother Michael, and together they eventually formed their own horn-dominated musical outfits, Dreams and The Brecker Brothers. Jerry Weiss went on to start the similarly-styled group Ambergris.

Answer the following question by taking a quote from the article: what was the Al Kooper era?
Al Kooper was the group's initial bandleader, having insisted on that position based on his experiences with the Blues Project,