What happens to Dutch ethnic identity after several generations in America? William Vandever (1817-1893) illustrates at least one path of acculturation. He was a Congressman twice--first from Iowa, later from California. During the Civil War, he raised a Union regiment from Iowa and was a general by the time the war ended. In the 1870s he was a U.S. Indian Inspector. His Dutchness, though, persisted through his self-identification as a devout Presbyterian--in the greater Reformed tradition of his Dutch ancestors of the 17th century.
Douglas Firth Anderson, "William Vandever: Presbyterian, Congressman, General," in Dutch Americans and War: United States and Abroad, eds. Robert P. Swierenga, Nella Kennedy, and Lisa Zylstra (Holland, MI: Van Raalte Press, 2014): 53-66.