My great grandfather Henry Gustave Zabel was born Hardrushben, Prussia about 1836. His wife, Eliza, born in Gahler, Prussia about 1837. Two children Henry Gustave, 1864 in Gahler and Margareta, 1867. Emigrated to London about 1868. Was a baker and died in London in 1873.
I do not know if this will be of any value as I have not yet seen a map with those towns on it, but thought I would share with you anyway. Rgds.