Born in Zempelburg, Germany, on November 26, 1869, Benke was the son of Carl Edward and Wilhelmiene Henrietta Behnke. (Hermann anglicized the surname while at school.) His father, a mason, immigrated first to the United States in June 1872 and sent for his wife and children four months later. The family moved a great deal, depending upon the availability of employment for Carl. A few years were spent on a farm near the western edge of Manitowoc County until Wilhelmiene demanded relocation after young Hermann was unable to scare a snake away from one of his two sisters.

Eventually the family made its way to Kansas where they settled near Odin. Hermann finished school and became a teacher at age seventeen.  His hobbies were botany and photography. In 1894 he moved to Dotyville, Wisconsin, and began taking photographs as well as returning to the teaching profession in Potter and then Wells. He built a general store/post office in Wells, too, and his parents and sister Bertha lived with him and helped run the business. During summer breaks from school teaching he traveled around Manitowoc County taking photographs of families and businesses. After their parents’ deaths, Hermann and Bertha sold the business and moved to Manitowoc where Bertha died in 1906 at Holy Family Hospital. 

On his own in Manitowoc, Benke took advantage of the penny postcard craze and made a suitable living photographing the city's scenes and events and then printing postcards. Some were sent to Germany for hand coloring and returned to Manitowoc for sale, often in batches of thousands. Benke was well known for producing special event postcards.  When a convention was in town he would photograph the parade or city decorations and have a postcard available for attendees the next day.

Benke arranged his business so he could continue his botanical studies and allow ample time for travel. A lifelong friend, William F. C. Grams of Chicago, often accompanied him, both men sharing an interest in photography and botany. Benke also followed local politics and was a supporter of Manitowoc’s Socialist mayor, Henry Stolze, at the time when the city was pursuing ownership of public utilities.

When postage rose on postcards the demand dwindled, so Benke moved to Illinois. Living first in Elgin and then Chicago, he stayed in touch with Manitowoc, visiting often. He supported the establishment of a civic center and donated his camera, the only one he ever used, to the fledgling institution.

Benke’s legacy is the capture of thousands of images of turn of the century Manitowoc and Manitowoc County. Some grace the walls of the Manitowoc County Courthouse, others continue as postcards avidly collected from antique shops. Manitowoc Public Library includes hundreds of Benke’s images in its digitized Local History Photograph Collection. Some postcards and enlargements of postcard images are displayed, too. His short autobiography, Life sketches, 1849-1946, is found in the Library’s Manitowoc Collection.