This is a brief history from the English District's web site:
The English District is one of thirty-five districts of The Lutheran Church--Missouri Synod. At one time the English District was an independent Lutheran Synod in North America, organized in 1888 as the "English Evangelical Lutheran Synod of Missouri." Its history goes back to colonial times.
In the early days of Lutheranism in the United States, the Henkels, a prominent Lutheran family, provided pastoral leadership for the church in Virginia. The family was concerned about Lutheran confessional teaching. In 1851, the Henkel family published the first English edition of the Book of Concord, the Lutheran Confessions. Members of the family were responsible for establishing several synods of the Evangelical Lutheran Church. One of those synods, the Tennessee Synod, was organized in 1820 by Pastor Paul Henkel. The Tennessee Synod believed firmly in the authority of God's Word. It insisted on strong catechetical training within the congregations.
Immediately after the American Civil War, Pastor Polycarp Henkel, grandson of founding patriarch Paul Henkel, served as pastor of Zion Church, Gravelton, Missouri. The leaders of the Tennessee Synod learned of the existence of the Missouri Synod, a strong confessional synod headed by Dr. Carl F. W. Walther, with headquarters in St. Louis. Tennessee Synod pastors and laymen in Missouri invited Dr. WaltherTh to meet with them. In August of 1872, representatives of the “German Missouri Synod” met with the pastors and congregations of the Tennessee Synod at Zion in Gravelton. Dr. Walther presented sixteen theses that expressed the confession of the Missouri Synod. While the theses were in English, the discussions were conducted both in German and English since the Tennessee Synod members did not speak German. As a result of the meeting "The English Evangelical Lutheran Conference of Missouri" was organized. In 1888 the English Conference of the Tennessee Synod in Missouri was organized as a separate synod, the English Evangelical Lutheran Synod of Missouri. However, the new English Synod continued attempts to become one organically with "The German Evangelical Lutheran Synod of Missouri, Ohio, and Other States."
Finally in 1911, the English Synod was accepted into the “German Missouri Synod” as a non-geographic synodical district. The “English Synod of Missouri” did not want amalgamation, but it did want to be part of the Missouri Synod because of its confessional and scriptural Lutheran stance.
Ironically, my sister Judy and her family are members of Christ the Shepard, an English District church.
If you google "english lutheran church", you will find that there are many churches today that still have the name, "First English Lutheran Church". It was clearly an important transition for German families to drop the German and embrace English as the language for worship. World War I was a major cause for the demise of the German in the church.