The National Guard troops (about 2,000 of them, IIRC) brought the riots to an end, that's all.
There was a notorious case where some Marines were asked to "cover" an LAPD team entering a building to make an arrest.
In police parlance, "cover" means "point your weapons at the building." In Marine Corps parlance, "cover" means "lay down suppression fire while another element maneuvers."
The LAPD started screaming at the Marines to "CEASE FIRE, YOU %@R$@R$!"
The Marines stop shooting, and a rioter came out of the building with his hands in the air, saying "I'll come quietly, just don't shoot me!"