Shortly after the assassination of Martin Luther King, Jr (who oddly enough lacks a monument here in town), rioting broke out on the streets of Baltimore City. A Baltimore City police history page has more details:
When rioting did break out on Saturday, April 6, the Governor of Maryland, Spiro T. Agnew, called out thousands of National Guard troops and 500 Maryland State Police to quell the disturbance. When it was determined that the state forces could not control the riot, Agnew requested Federal troops from President Lyndon B. Johnson.
By Sunday evening, 5000 paratroopers, combat engineers, and artillerymen from the XVIII Airborne Corps in Fort Bragg, North Carolina, specially trained in riot control tactics, including sniper school, were on the streets of Baltimore with fixed bayonets, and equipped with chemical (CS) disperser backpacks. Two days later, they were joined by a Light Infantry Brigade from Fort Benning, Georgia. With all the police and troops on the streets, things began to calm down. The FBI reported that H. Rap Brown was in Baltimore driving a Ford Mustang with Broward County, Florida tags, and was assembling large groups of angry protesters and agitating them to escalate the rioting. In several instances, these disturbances were rapidly quelled through the skillful use of bayonets and chemical dispersers by the XVIII Airborne units. That unit did not fire a single round of ammunition and arrested more than 3,000 detainees, who were identified, tagged with bracelets, and delivered in cattle trucks to the Baltimore police precincts.