The National Guard is a reserve force of the U.S. military that is typically deployed by states in response to natural disasters, although it has been used in the past by presidents to help quell domestic unrest - including President George H.W. Bush during the Los Angeles riots in 1992.

From upholding civil rights rulings to quelling civil disturbances and even delivering mail, other presidents have sent out National Guard units.

National Guard troops are roaming the streets of Washington, D.C. after being deployed by President Donald Trump, who declared an emergency in the nation’s capital earlier this week. Around 800 National Guard members arrived in D.