Complex sentence: Adas Israel congregation (Washington, D.C.), with Isaac Stampel as Hazzan, was founded in 1869 by 69 members of the Washington Hebrew Congregation who objected to the Reform tendencies of the old congregation.
Split into simpler sentences: Adas Israel congregation (Washington, D.C.) was founded in 1869 by 69 members of the Washington Hebrew Congregation who objected to the congregation's move towards Reform. This congregation, which was called Adath Israel, was organized as a protest against the Reform tendencies of the old congregation.