Complex sentence: From 1850 to 1866, he contributed a series of newspapers in Richmond and Washington, D.C., primarily the Richmond Examiner, over which he assumed editorial control when the regular editor, John M. Daniel, left the country as U.S. Minister to Sardinia.
Split into simpler sentences: From 1850 to 1866, he contributed a series of newspapers in Richmond and Washington, D.C., primarily the Richmond Examiner. He took over as editor of the Examiner when the regular editor, John M. Daniel, left the country as U.S. Minister to Sardinia.