First recorded by The Intruders (US #78/R&B #14 1966).
Hit version by Peaches & Herb (US #46/R&B #11 1968).
From the wiki: “The Intruders were one of the first groups to have hit songs under the direction of songwriters and record producers Kenny Gamble and Leon Huff (Harold Melvin & The Blue Notes, The O’Jays), they had a major influence on the development of Philadelphia soul. In 1965, when Gamble and Huff first contemplated leaving the Cameo-Parkway record label to risk launching their own label, the vocalists on which they pinned all their hopes and venture capital were The Intruders.
“Gamble and Huff’s success with The Intruders helped convince Columbia Records to grant them the money to launch Philadelphia International. ‘(We’ll Be) United’ was the first charting song for The Intruders, peaking at #14 on the Billboard Soul chart, and #78 on the Billboard Hot 100, in 1966.