Complex sentence: From 1896 the department also hosted the command of the colonial Protection Force or "Schutztruppe" (after 1897 called the Supreme Command of the Protection Force), which until that time had been housed in the Navy Office (Reichsmarineamt).
Split into simpler sentences: From 1896 the department also commanded the colonial Protection Force or "Schutztruppe". Which up until that time had been housed in the Navy Office (Reichsmarineamt).