My 2xGreat Grandparents Carl Friedrich Martiens (ships carpenter) and Louisa Maria Martiens nee Zwicht.
They lived in Barth, Germany in Abt. 1837. Known children are Johann Heinrich born abt. 1832 Carl Johannes born 1837 Barth, Germany and my Great Grandfather Vollrath Gustav Christian born 1840 Barth, Germany married Maria Sophia Wilhelmine Hahn in Barth, Germany.
There are still eight children missing to Carl and Louisa. We know one son went to the U.S.A. But we do not know his first names. The family changed their name to Martiensen.