David Einhorn (November 10, 1809 – November 2, 1879) was a German-Jewish rabbi and leader of Reform Judaism in the United States. Einhorn was chosen in 1855 as the first rabbi of the Har Sinai Congregation in Baltimore, the oldest congregation in the United States that has been affiliated with the Reform movement since its inception. While there, he compiled a siddur in German and Hebrew, one of the early Reform Jewish prayerbooks in the United States. (The siddur, later translated to English, became one of the progenitors of the Reform Movement's Union Prayer Book.) In 1861, Einhorn's life was threatened by a mob angered by his strong abolitionist anti-slavery views, and was forced to flee to Philadelphia. There he became rabbi of Reform Congregation Keneseth Israel. He moved to New York City in 1866, where he became rabbi of Congregation Adath Israel. (from his wikipedia article)