Analysis of information sources in references of the Wikipedia article "April 1968" in English language version.
Long before rioting broke out in Baltimore, Governor Spiro Agnew and his staff worried that their biggest threat came from Washington; at 11:00 P.M. on Friday, he alerted the Maryland National Guard and called General George Gelston to duty, deploying him not to Baltimore but to the state armory in Silver Spring, a D.C. suburb. The Guard even had an emergency plan, Operation Tango, for riots that spread north from the District.